diff --git a/docs/usage/nnc.rst b/docs/usage/nnc.rst
index 21ed2aa60..71b49f6f5 100644
--- a/docs/usage/nnc.rst
+++ b/docs/usage/nnc.rst
@@ -55,12 +55,12 @@ to an Eclipse include file:
    nnc_df = nnc.df(resdatafiles)
    nnc_df["TRANM"] = 0.1  # Reduce all NNC transmissibilities
 
-   nnc.df2ecl_editnnc(nnc_df, filename="editnnc.inc")
+   nnc.df2res_editnnc(nnc_df, filename="editnnc.inc")
 
 and the contents of the exported file can be:
 
 ..
-   print(nnc.df2ecl_editnnc(nnc.df(resdatafiles).head(4).assign(TRANM=0.1)))
+   print(nnc.df2res_editnnc(nnc.df(resdatafiles).head(4).assign(TRANM=0.1)))
 
 .. code-block:: console
 
diff --git a/res2df/common.py b/res2df/common.py
index 122ddd273..5fa3b8818 100644
--- a/res2df/common.py
+++ b/res2df/common.py
@@ -187,7 +187,7 @@ def datetime_to_eclipsedate(
     return string.replace("00:00:00", "").strip()
 
 
-def ecl_keyworddata_to_df(
+def res_keyworddata_to_df(
     deck,
     keyword: str,
     renamer: Optional[Dict[str, Union[str, List[str]]]] = None,
@@ -353,7 +353,7 @@ def parse_opmio_date_rec(record: "opm.io.DeckRecord") -> datetime.date:
     day = record[0].get_int(0)
     month = record[1].get_str(0)
     year = record[2].get_int(0)
-    return datetime.date(year=year, month=parse_ecl_month(month), day=day)
+    return datetime.date(year=year, month=parse_res_month(month), day=day)
 
 
 def parse_opmio_tstep_rec(record: "opm.io.DeckRecord") -> List[Union[float, int]]:
@@ -519,7 +519,7 @@ def df2ecl(
     """Generate resdata include strings from dataframes in res2df format.
 
     This function hands over the actual text generation pr. keyword
-    to functions named df2ecl_<keywordname> in the calling module.
+    to functions named df2res_<keywordname> in the calling module.
 
     These functions may again use generic_ecltable() from this module
     for the actual string construction.
@@ -611,7 +611,7 @@ def df2ecl(
         string += comment_formatter(comments["master"])
     for keyword in keywords:
         # Construct the associated function names
-        function_name = "df2ecl_" + keyword.lower()
+        function_name = "df2res_" + keyword.lower()
         function = getattr(calling_module, function_name)
         if keyword in comments:
             string += function(dataframe, comments[keyword])
diff --git a/res2df/equil.py b/res2df/equil.py
index fc3df876e..9928630af 100644
--- a/res2df/equil.py
+++ b/res2df/equil.py
@@ -141,7 +141,7 @@ def rsvd_fromdeck(
     """
     if "EQLDIMS" not in deck:
         deck = inferdims.inject_xxxdims_ntxxx("EQLDIMS", "NTEQUL", deck, ntequl)
-    return common.ecl_keyworddata_to_df(
+    return common.res_keyworddata_to_df(
         deck, "RSVD", renamer=RENAMERS["RSVD"], recordcountername="EQLNUM"
     )
 
@@ -158,7 +158,7 @@ def rvvd_fromdeck(
     """
     if "EQLDIMS" not in deck:
         deck = inferdims.inject_xxxdims_ntxxx("EQLDIMS", "NTEQUL", deck, ntequl)
-    return common.ecl_keyworddata_to_df(
+    return common.res_keyworddata_to_df(
         deck, "RVVD", renamer=RENAMERS["RVVD"], recordcountername="EQLNUM"
     )
 
@@ -175,7 +175,7 @@ def pbvd_fromdeck(
     """
     if "EQLDIMS" not in deck:
         deck = inferdims.inject_xxxdims_ntxxx("EQLDIMS", "NTEQUL", deck, ntequl)
-    return common.ecl_keyworddata_to_df(
+    return common.res_keyworddata_to_df(
         deck, "PBVD", renamer=RENAMERS["PBVD"], recordcountername="EQLNUM"
     )
 
@@ -192,7 +192,7 @@ def pdvd_fromdeck(
     """
     if "EQLDIMS" not in deck:
         deck = inferdims.inject_xxxdims_ntxxx("EQLDIMS", "NTEQUL", deck, ntequl)
-    return common.ecl_keyworddata_to_df(
+    return common.res_keyworddata_to_df(
         deck, "PDVD", renamer=RENAMERS["PDVD"], recordcountername="EQLNUM"
     )
 
@@ -264,7 +264,7 @@ def equil_fromdeck(
         raise ValueError(f"Could not determine phase configuration, got '{phases}'")
     columnrenamer = RENAMERS[phases_from_deck(deck)]
 
-    dataframe = common.ecl_keyworddata_to_df(
+    dataframe = common.res_keyworddata_to_df(
         deck, "EQUIL", renamer=columnrenamer, recordcountername="EQLNUM"
     )
 
@@ -392,7 +392,7 @@ def df2ecl(
     return string
 
 
-def df2ecl_equil(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
+def df2res_equil(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
     """Print EQUIL keyword with data
 
     Args:
@@ -427,7 +427,7 @@ def df2ecl_equil(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
     )
 
 
-def df2ecl_rsvd(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
+def df2res_rsvd(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
     """Print RSVD keyword with data
 
     This data consists of one table (rs as a function
@@ -437,10 +437,10 @@ def df2ecl_rsvd(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
         dframe: Containing RSVD data
         comment Text that will be included as a comment
     """
-    return _df2ecl_equilfuncs("RSVD", dframe, comment)
+    return _df2res_equilfuncs("RSVD", dframe, comment)
 
 
-def df2ecl_rvvd(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
+def df2res_rvvd(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
     """Print RVVD keyword with data
 
     This data consists of one table (rv as a function
@@ -450,10 +450,10 @@ def df2ecl_rvvd(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
         dframe: Containing RVVD data
         comment: Text that will be included as a comment
     """
-    return _df2ecl_equilfuncs("RVVD", dframe, comment)
+    return _df2res_equilfuncs("RVVD", dframe, comment)
 
 
-def df2ecl_pbvd(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
+def df2res_pbvd(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
     """Print PBVD keyword with data
 
     Bubble-point versus depth
@@ -465,10 +465,10 @@ def df2ecl_pbvd(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
         dframe: Containing PBVD data
         comment: Text that will be included as a comment
     """
-    return _df2ecl_equilfuncs("PBVD", dframe, comment)
+    return _df2res_equilfuncs("PBVD", dframe, comment)
 
 
-def df2ecl_pdvd(dframe: pd.DataFrame, comment: Optional[str] = None):
+def df2res_pdvd(dframe: pd.DataFrame, comment: Optional[str] = None):
     """Print PDVD keyword with data.
 
     Dew-point versus depth.
@@ -480,13 +480,13 @@ def df2ecl_pdvd(dframe: pd.DataFrame, comment: Optional[str] = None):
         dframe: Containing PDVD data
         comment: Text that will be included as a comment
     """
-    return _df2ecl_equilfuncs("PDVD", dframe, comment)
+    return _df2res_equilfuncs("PDVD", dframe, comment)
 
 
-def _df2ecl_equilfuncs(
+def _df2res_equilfuncs(
     keyword: str, dframe: pd.DataFrame, comment: Optional[str] = None
 ) -> str:
-    """Internal function to be used by df2ecl_<keyword>() functions"""
+    """Internal function to be used by df2res_<keyword>() functions"""
     if dframe.empty:
         return "-- No data!"
     string = f"{keyword}\n"
@@ -500,7 +500,7 @@ def _df2ecl_equilfuncs(
     else:
         subset = dframe[dframe["KEYWORD"] == keyword]
 
-    def _df2ecl_equilfuncs_eqlnum(dframe: pd.DataFrame) -> str:
+    def _df2res_equilfuncs_eqlnum(dframe: pd.DataFrame) -> str:
         """Print one equilibriation function table for a specific
         EQLNUM
 
@@ -519,5 +519,5 @@ def _df2ecl_equilfuncs_eqlnum(dframe: pd.DataFrame) -> str:
     subset = subset.set_index("EQLNUM").sort_index()
     for eqlnum in subset.index.unique():
         string += f"-- EQLNUM: {eqlnum}\n"
-        string += _df2ecl_equilfuncs_eqlnum(subset[subset.index == eqlnum])
+        string += _df2res_equilfuncs_eqlnum(subset[subset.index == eqlnum])
     return string + "\n"
diff --git a/res2df/fipreports.py b/res2df/fipreports.py
index 493a3073d..8a4df5787 100644
--- a/res2df/fipreports.py
+++ b/res2df/fipreports.py
@@ -11,7 +11,7 @@
 import pandas as pd
 
 from res2df import ResdataFiles, getLogger_res2csv
-from res2df.common import parse_ecl_month, write_dframe_stdout_file
+from res2df.common import parse_res_month, write_dframe_stdout_file
 
 logger = logging.getLogger(__name__)
 
@@ -126,7 +126,7 @@ def df(prtfile: Union[str, ResdataFiles], fipname: str = "FIPNUM") -> pd.DataFra
     region_index = None
     date = None
 
-    ecl_datematcher = re.compile(r"\s\sREPORT\s+\d+\s+(\d+)\s+(\w+)\s+(\d+)")
+    res_datematcher = re.compile(r"\s\sREPORT\s+\d+\s+(\d+)\s+(\w+)\s+(\d+)")
     opm_datematcher = re.compile(r"Starting time step.*? date = (\d+)-(\w+)-(\d+)\s*")
 
     # When case insensitive, this one works with both Eclipse100 and OPM:
@@ -144,7 +144,7 @@ def df(prtfile: Union[str, ResdataFiles], fipname: str = "FIPNUM") -> pd.DataFra
             fipname,
         )
         for line in prt_fh:
-            matcheddate = re.match(ecl_datematcher, line)
+            matcheddate = re.match(res_datematcher, line)
             if matcheddate is None:
                 matcheddate = re.match(opm_datematcher, line)
                 if matcheddate is not None:
@@ -152,7 +152,7 @@ def df(prtfile: Union[str, ResdataFiles], fipname: str = "FIPNUM") -> pd.DataFra
             if matcheddate is not None:
                 newdate = datetime.date(
                     year=int(matcheddate.group(3)),
-                    month=parse_ecl_month(matcheddate.group(2).upper()),
+                    month=parse_res_month(matcheddate.group(2).upper()),
                     day=int(matcheddate.group(1)),
                 )
                 if newdate != date:
diff --git a/res2df/nnc.py b/res2df/nnc.py
index a798bc78e..015c28cf2 100644
--- a/res2df/nnc.py
+++ b/res2df/nnc.py
@@ -200,7 +200,7 @@ def fill_parser(parser: argparse.ArgumentParser) -> argparse.ArgumentParser:
     return parser
 
 
-def df2ecl_editnnc(
+def df2res_editnnc(
     nnc_df: pd.DataFrame, filename: Optional[str] = None, nocomments: bool = False
 ) -> str:
     """Write an EDITNNC keyword
diff --git a/res2df/pvt.py b/res2df/pvt.py
index 864c1c536..60bf10f43 100644
--- a/res2df/pvt.py
+++ b/res2df/pvt.py
@@ -81,7 +81,7 @@ def pvtw_fromdeck(
     """
     if "TABDIMS" not in deck:
         deck = inferdims.inject_xxxdims_ntxxx("TABDIMS", "NTPVT", deck, ntpvt)
-    return common.ecl_keyworddata_to_df(
+    return common.res_keyworddata_to_df(
         deck, "PVTW", renamer=RENAMERS["PVTW"], recordcountername="PVTNUM"
     )
 
@@ -98,7 +98,7 @@ def density_fromdeck(
     """
     if "TABDIMS" not in deck:
         deck = inferdims.inject_xxxdims_ntxxx("TABDIMS", "NTPVT", deck, ntpvt)
-    return common.ecl_keyworddata_to_df(
+    return common.res_keyworddata_to_df(
         deck, "DENSITY", renamer=RENAMERS["DENSITY"], recordcountername="PVTNUM"
     )
 
@@ -115,7 +115,7 @@ def rock_fromdeck(
     """
     if "TABDIMS" not in deck:
         deck = inferdims.inject_xxxdims_ntxxx("TABDIMS", "NTPVT", deck, ntpvt)
-    return common.ecl_keyworddata_to_df(
+    return common.res_keyworddata_to_df(
         deck, "ROCK", renamer=RENAMERS["ROCK"], recordcountername="PVTNUM"
     )
 
@@ -132,7 +132,7 @@ def pvto_fromdeck(
     """
     if "TABDIMS" not in deck:
         deck = inferdims.inject_xxxdims_ntxxx("TABDIMS", "NTPVT", deck, ntpvt)
-    pvto_df = common.ecl_keyworddata_to_df(
+    pvto_df = common.res_keyworddata_to_df(
         deck, "PVTO", renamer=RENAMERS["PVTO"], emptyrecordcountername="PVTNUM"
     )
     return pvto_df
@@ -150,7 +150,7 @@ def pvdo_fromdeck(
     """
     if "TABDIMS" not in deck:
         deck = inferdims.inject_xxxdims_ntxxx("TABDIMS", "NTPVT", deck, ntpvt)
-    pvdg_df = common.ecl_keyworddata_to_df(
+    pvdg_df = common.res_keyworddata_to_df(
         deck, "PVDO", renamer=RENAMERS["PVDO"], recordcountername="PVTNUM"
     )
     return pvdg_df
@@ -168,7 +168,7 @@ def pvdg_fromdeck(
     """
     if "TABDIMS" not in deck:
         deck = inferdims.inject_xxxdims_ntxxx("TABDIMS", "NTPVT", deck, ntpvt)
-    pvdg_df = common.ecl_keyworddata_to_df(
+    pvdg_df = common.res_keyworddata_to_df(
         deck, "PVDG", renamer=RENAMERS["PVDG"], recordcountername="PVTNUM"
     )
     return pvdg_df
@@ -186,7 +186,7 @@ def pvtg_fromdeck(
     """
     if "TABDIMS" not in deck:
         deck = inferdims.inject_xxxdims_ntxxx("TABDIMS", "NTPVT", deck, ntpvt)
-    pvtg_df = common.ecl_keyworddata_to_df(
+    pvtg_df = common.res_keyworddata_to_df(
         deck, "PVTG", renamer=RENAMERS["PVTG"], emptyrecordcountername="PVTNUM"
     )
     return pvtg_df
@@ -351,7 +351,7 @@ def df2ecl(
     )
 
 
-def df2ecl_rock(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
+def df2res_rock(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
     """Print ROCK keyword with data
 
     Args:
@@ -379,7 +379,7 @@ def df2ecl_rock(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
     return string + "\n"
 
 
-def df2ecl_density(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
+def df2res_density(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
     """Print DENSITY keyword with data
 
     Args:
@@ -408,7 +408,7 @@ def df2ecl_density(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
     return string + "\n"
 
 
-def df2ecl_pvtw(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
+def df2res_pvtw(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
     """Print PVTW keyword with data
 
     PVTW is one line/record with data for a reference pressure
@@ -444,7 +444,7 @@ def df2ecl_pvtw(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
     return string + "\n"
 
 
-def df2ecl_pvtg(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
+def df2res_pvtg(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
     """Print PVTG keyword with data
 
     Args:
@@ -503,7 +503,7 @@ def _pvtg_pvtnum_pg(dframe):
     return string + "\n"
 
 
-def df2ecl_pvdg(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
+def df2res_pvdg(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
     """Print PVDG keyword with data
 
     This data consists of one table (volumefactor and visosity
@@ -553,7 +553,7 @@ def _pvdg_pvtnum(dframe):
     return string + "\n"
 
 
-def df2ecl_pvdo(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
+def df2res_pvdo(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
     """Print PVDO keyword with data
 
     Args:
@@ -600,7 +600,7 @@ def _pvdo_pvtnum(dframe: pd.DataFrame) -> str:
     return string + "\n"
 
 
-def df2ecl_pvto(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
+def df2res_pvto(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
     """Print PVTO-data from a dataframe
 
     Args:
diff --git a/res2df/satfunc.py b/res2df/satfunc.py
index a7ba81b56..d3f9b517e 100644
--- a/res2df/satfunc.py
+++ b/res2df/satfunc.py
@@ -104,7 +104,7 @@ def df(
     for keyword in wanted_keywords:
         frames.append(
             interpolate_defaults(
-                common.ecl_keyworddata_to_df(
+                common.res_keyworddata_to_df(
                     deck, keyword, renamer=RENAMERS[keyword], recordcountername="SATNUM"
                 ).assign(KEYWORD=keyword)
             )
@@ -268,87 +268,87 @@ def df2ecl(
     return string
 
 
-def df2ecl_swof(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
+def df2res_swof(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
     """Print SWOF data. Used by df2ecl().
 
     Args:
         dframe: Containing SWOF data
         comment: Text that will be included as a comment
     """
-    return _df2ecl_satfuncs("SWOF", dframe, comment)
+    return _df2res_satfuncs("SWOF", dframe, comment)
 
 
-def df2ecl_sgof(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
+def df2res_sgof(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
     """Print SGOF data. Used by df2ecl().
 
     Args:
         dframe: Containing SGOF data
         comment: Text that will be included as a comment
     """
-    return _df2ecl_satfuncs("SGOF", dframe, comment)
+    return _df2res_satfuncs("SGOF", dframe, comment)
 
 
-def df2ecl_sgfn(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
+def df2res_sgfn(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
     """Print SGFN data. Used by df2ecl().
 
     Args:
         dframe: Containing SGFN data
         comment: Text that will be included as a comment
     """
-    return _df2ecl_satfuncs("SGFN", dframe, comment)
+    return _df2res_satfuncs("SGFN", dframe, comment)
 
 
-def df2ecl_sgwfn(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
+def df2res_sgwfn(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
     """Print SGWFN data. Used by df2ecl().
 
     Args:
         dframe: Containing SGWFN data
         comment: Text that will be included as a comment
     """
-    return _df2ecl_satfuncs("SGWFN", dframe, comment)
+    return _df2res_satfuncs("SGWFN", dframe, comment)
 
 
-def df2ecl_swfn(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
+def df2res_swfn(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
     """Print SWFN data. Used by df2ecl().
 
     Args:
         dframe: Containing SWFN data
         comment: Text that will be included as a comment
     """
-    return _df2ecl_satfuncs("SWFN", dframe, comment)
+    return _df2res_satfuncs("SWFN", dframe, comment)
 
 
-def df2ecl_slgof(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
+def df2res_slgof(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
     """Print SLGOF data. Used by df2ecl().
 
     Args:
         dframe: Containing SLGOF data
         comment: Text that will be included as a comment
     """
-    return _df2ecl_satfuncs("SLGOF", dframe, comment)
+    return _df2res_satfuncs("SLGOF", dframe, comment)
 
 
-def df2ecl_sof2(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
+def df2res_sof2(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
     """Print SOF2 data. Used by df2ecl().
 
     Args:
         dframe: Containing SOF2 data
         comment: Text that will be included as a comment
     """
-    return _df2ecl_satfuncs("SOF2", dframe, comment)
+    return _df2res_satfuncs("SOF2", dframe, comment)
 
 
-def df2ecl_sof3(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
+def df2res_sof3(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
     """Print SOF3 data. Used by df2ecl().
 
     Args:
         dframe: Containing SOF3 data
         comment: Text that will be included as a comment
     """
-    return _df2ecl_satfuncs("SOF3", dframe, comment)
+    return _df2res_satfuncs("SOF3", dframe, comment)
 
 
-def _df2ecl_satfuncs(
+def _df2res_satfuncs(
     keyword: str, dframe: pd.DataFrame, comment: Optional[str] = None
 ) -> str:
     if dframe.empty:
@@ -366,7 +366,7 @@ def _df2ecl_satfuncs(
     subset = subset.set_index("SATNUM").sort_index()
 
     # Make a function that is to be called for each SATNUM
-    def _df2ecl_satfuncs_satnum(keyword, dframe):
+    def _df2res_satfuncs_satnum(keyword, dframe):
         """Print one saturation function for one specific SATNUM"""
         col_headers = RENAMERS[keyword]["DATA"]
         string = (
@@ -380,5 +380,5 @@ def _df2ecl_satfuncs_satnum(keyword, dframe):
     # Loop over every SATNUM
     for satnum in subset.index.unique():
         string += f"-- SATNUM: {satnum}\n"
-        string += _df2ecl_satfuncs_satnum(keyword, subset[subset.index == satnum])
+        string += _df2res_satfuncs_satnum(keyword, subset[subset.index == satnum])
     return string + "\n"
diff --git a/res2df/summary.py b/res2df/summary.py
index 008a09808..690e768ae 100644
--- a/res2df/summary.py
+++ b/res2df/summary.py
@@ -403,7 +403,7 @@ def df(
     )
 
     # dframe = eclsum.pandas_frame(time_index_arg, column_keys)
-    dframe = _libecl_eclsum_pandas_frame(eclsum, time_index_arg, column_keys)
+    dframe = _libres_eclsum_pandas_frame(eclsum, time_index_arg, column_keys)
 
     logger.info(
         "Dataframe with smry data ready, %d columns and %d rows",
@@ -701,11 +701,11 @@ def df2eclsum(
         raise ValueError(f"Do not use dots in casename {casename}")
 
     dframe = _fix_dframe_for_libecl(dframe)
-    return _libecl_eclsum_from_pandas(casename, dframe)
+    return _libres_eclsum_from_pandas(casename, dframe)
     # return Summary.from_pandas(casename, dframe)
 
 
-def _libecl_eclsum_pandas_frame(
+def _libres_eclsum_pandas_frame(
     eclsum: Summary,
     time_index: Optional[Union[List[dt.date], List[dt.datetime]]] = None,
     column_keys: Optional[List[str]] = None,
@@ -754,7 +754,7 @@ def _libecl_eclsum_pandas_frame(
     return frame
 
 
-def _libecl_eclsum_from_pandas(
+def _libres_eclsum_from_pandas(
     case: str,
     frame: pd.DataFrame,
     dims: Optional[List[int]] = None,
@@ -781,18 +781,18 @@ def _libecl_eclsum_from_pandas(
         header_list = Summary._compile_headers_list(headers, dims)
     if dims is None:
         dims = [1, 1, 1]
-    ecl_sum = Summary.writer(case, start_time, dims[0], dims[1], dims[2])
+    res_sum = Summary.writer(case, start_time, dims[0], dims[1], dims[2])
     for keyword, wgname, num, unit in header_list:
         var_list.append(
-            ecl_sum.add_variable(keyword, wgname=wgname, num=num, unit=unit).getKey1()
+            res_sum.add_variable(keyword, wgname=wgname, num=num, unit=unit).getKey1()
         )
 
     for idx, time in enumerate(frame.index):
         days = (time - start_time).days
-        t_step = ecl_sum.add_t_step(idx + 1, days)
+        t_step = res_sum.add_t_step(idx + 1, days)
         for var in var_list:
             t_step[var] = frame.iloc[idx][var]
-    return ecl_sum
+    return res_sum
 
 
 def fill_parser(parser: argparse.ArgumentParser) -> argparse.ArgumentParser:
diff --git a/res2df/vfp/_vfpcommon.py b/res2df/vfp/_vfpcommon.py
index f63335ba5..062a2f068 100755
--- a/res2df/vfp/_vfpcommon.py
+++ b/res2df/vfp/_vfpcommon.py
@@ -195,12 +195,12 @@ def _write_vfp_range(
     if var_type != "UNDEFINED":
         var_type_str = var_type
 
-    ecl_str = f"-- {var_type_str} units - {unit_type} ( {len(values)} values )\n"
+    res_str = f"-- {var_type_str} units - {unit_type} ( {len(values)} values )\n"
     for i, value in enumerate(values):
-        ecl_str += format % value
+        res_str += format % value
         if (i + 1) % values_per_line == 0 and i < len(values) - 1:
-            ecl_str += "\n"
-    ecl_str += " /\n"
-    ecl_str += "\n"
+            res_str += "\n"
+    res_str += " /\n"
+    res_str += "\n"
 
-    return ecl_str
+    return res_str
diff --git a/res2df/vfp/_vfpinj.py b/res2df/vfp/_vfpinj.py
index 76e75af88..83add8613 100755
--- a/res2df/vfp/_vfpinj.py
+++ b/res2df/vfp/_vfpinj.py
@@ -564,15 +564,15 @@ def _write_basic_record(
     if unit_type != "DEFAULT":
         unit_type_str = unit_type
 
-    ecl_str = "-- Table  Datum Depth  Rate Type  THP Type  UNITS     TAB Type\n"
-    ecl_str += "-- -----  -----------  ---------  --------  --------  --------\n"
-    ecl_str += f"   {tableno:5d}"
-    ecl_str += f"  {datum:11.1f}"
-    ecl_str += f"  {flo_type:>9s}"
-    ecl_str += f"  {pressure_type:>8s}"
-    ecl_str += f"  {unit_type_str:>8s}"
-    ecl_str += f"  {tab_type:>8s} /\n\n"
-    return ecl_str
+    res_str = "-- Table  Datum Depth  Rate Type  THP Type  UNITS     TAB Type\n"
+    res_str += "-- -----  -----------  ---------  --------  --------  --------\n"
+    res_str += f"   {tableno:5d}"
+    res_str += f"  {datum:11.1f}"
+    res_str += f"  {flo_type:>9s}"
+    res_str += f"  {pressure_type:>8s}"
+    res_str += f"  {unit_type_str:>8s}"
+    res_str += f"  {tab_type:>8s} /\n\n"
+    return res_str
 
 
 def _write_table(
@@ -589,23 +589,23 @@ def _write_table(
         values_per_line: Number of values per line in output
     """
 
-    ecl_str = ""
+    res_str = ""
     for idx, row in table.iterrows():
-        ecl_str += f"{idx:2d}"
+        res_str += f"{idx:2d}"
         no_flo = len(table.loc[idx].to_list())
         for n, value in enumerate(table.loc[idx].to_list()):
-            ecl_str += format % value
+            res_str += format % value
             if (n + 1) % values_per_line == 0:
                 if n < no_flo - 1:
-                    ecl_str += "\n"
-                    ecl_str += " " * 2
+                    res_str += "\n"
+                    res_str += " " * 2
                 else:
-                    ecl_str += "\n"
+                    res_str += "\n"
             elif n == no_flo - 1:
-                ecl_str += "\n"
-        ecl_str += "/\n"
+                res_str += "\n"
+        res_str += "/\n"
 
-    return ecl_str
+    return res_str
 
 
 def _write_table_records(
@@ -624,7 +624,7 @@ def _write_table_records(
         values_per_line: Number of values per line in output
     """
 
-    ecl_str = ""
+    res_str = ""
     no_records = len(thp_indices)
     no_flow_values = table.size // no_records
     if table.size % no_records > 0:
@@ -634,21 +634,21 @@ def _write_table_records(
 
     for row in range(0, no_records):
         thp = thp_indices[row]
-        ecl_str += f"{thp:2d}"
+        res_str += f"{thp:2d}"
         for n, value in enumerate(table[row, :]):
-            ecl_str += format % value
+            res_str += format % value
             if (n + 1) % values_per_line == 0:
                 if n < no_flow_values - 1:
-                    ecl_str += "\n"
-                    ecl_str += " " * 2
+                    res_str += "\n"
+                    res_str += " " * 2
                 else:
-                    ecl_str += "\n"
+                    res_str += "\n"
             elif n == no_flow_values - 1:
-                ecl_str += "\n"
+                res_str += "\n"
 
-        ecl_str += "/\n"
+        res_str += "/\n"
 
-    return ecl_str
+    return res_str
 
 
 def df2ecl(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
@@ -670,16 +670,16 @@ def df2ecl(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
     unit_type = vfpinj_data["UNIT_TYPE"]
 
     # Write dataframe to string with Eclipse format for VFPINJ
-    ecl_str = "VFPINJ\n"
+    res_str = "VFPINJ\n"
     if comment:
-        ecl_str += common.comment_formatter(comment)
+        res_str += common.comment_formatter(comment)
     else:
-        ecl_str += "\n"
+        res_str += "\n"
 
     unit_value = vfpinj_data["UNIT_TYPE"].value
     if vfpinj_data["UNIT_TYPE"] == UNITTYPE.DEFAULT:
         unit_value = "1*"
-    ecl_str += _write_basic_record(
+    res_str += _write_basic_record(
         vfpinj_data["TABLE_NUMBER"],
         vfpinj_data["DATUM"],
         vfpinj_data["RATE_TYPE"].value,
@@ -687,22 +687,22 @@ def df2ecl(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
         unit_value,
         vfpinj_data["TAB_TYPE"].value,
     )
-    ecl_str += _write_vfp_range(
+    res_str += _write_vfp_range(
         vfpinj_data["FLOW_VALUES"],
         rate_type.value,
         VFPINJ_UNITS[unit_type.value]["FLO"][rate_type.value],
         "%10.6g",
     )
-    ecl_str += _write_vfp_range(
+    res_str += _write_vfp_range(
         vfpinj_data["THP_VALUES"],
         thp_type.value,
         VFPINJ_UNITS[unit_type.value]["THP"][thp_type.value],
         "%10.6g",
     )
-    ecl_str += _write_table_records(
+    res_str += _write_table_records(
         vfpinj_data["THP_INDICES"],
         vfpinj_data["BHP_TABLE"],
         "%10.6g",
     )
 
-    return ecl_str
+    return res_str
diff --git a/res2df/vfp/_vfpprod.py b/res2df/vfp/_vfpprod.py
index 4e2573127..d3383fcde 100755
--- a/res2df/vfp/_vfpprod.py
+++ b/res2df/vfp/_vfpprod.py
@@ -834,20 +834,20 @@ def _write_basic_record(
     if alq_type != "UNDEFINED":
         alq_type_str = alq_type
 
-    ecl_str = "-- Table  Datum Depth  Rate Type  WFR Type  "
-    ecl_str += "GFR Type  THP Type  ALQ Type  UNITS   TAB Type\n"
-    ecl_str += "-- -----  -----------  ---------  --------  "
-    ecl_str += "--------  --------  --------  ------  --------\n"
-    ecl_str += f"   {tableno:5d}"
-    ecl_str += f"  {datum:11.1f}"
-    ecl_str += f"   {flo_type:>8s}"
-    ecl_str += f"  {wfr_type:>8s}"
-    ecl_str += f"  {gfr_type:>8s}"
-    ecl_str += f"  {pressure_type:>8s}"
-    ecl_str += f"  {alq_type_str:>8s}"
-    ecl_str += f"  {unit_type:>6s}"
-    ecl_str += f"  {tab_type:>8s} /\n\n"
-    return ecl_str
+    res_str = "-- Table  Datum Depth  Rate Type  WFR Type  "
+    res_str += "GFR Type  THP Type  ALQ Type  UNITS   TAB Type\n"
+    res_str += "-- -----  -----------  ---------  --------  "
+    res_str += "--------  --------  --------  ------  --------\n"
+    res_str += f"   {tableno:5d}"
+    res_str += f"  {datum:11.1f}"
+    res_str += f"   {flo_type:>8s}"
+    res_str += f"  {wfr_type:>8s}"
+    res_str += f"  {gfr_type:>8s}"
+    res_str += f"  {pressure_type:>8s}"
+    res_str += f"  {alq_type_str:>8s}"
+    res_str += f"  {unit_type:>6s}"
+    res_str += f"  {tab_type:>8s} /\n\n"
+    return res_str
 
 
 def _write_table(
@@ -864,23 +864,23 @@ def _write_table(
         values_per_line: Number of values per line in output
     """
 
-    ecl_str = ""
+    res_str = ""
     for idx, row in table.iterrows():
-        ecl_str += f"{idx[0]:2d} {idx[1]:2d} {idx[2]:2d} {idx[3]:2d}"
+        res_str += f"{idx[0]:2d} {idx[1]:2d} {idx[2]:2d} {idx[3]:2d}"
         no_flo = len(table.loc[idx].to_list())
         for n, value in enumerate(table.loc[idx].to_list()):
-            ecl_str += format % value
+            res_str += format % value
             if (n + 1) % values_per_line == 0:
                 if n < no_flo - 1:
-                    ecl_str += "\n"
-                    ecl_str += " " * 11
+                    res_str += "\n"
+                    res_str += " " * 11
                 else:
-                    ecl_str += "\n"
+                    res_str += "\n"
             elif n == no_flo - 1:
-                ecl_str += "\n"
-        ecl_str += "/\n"
+                res_str += "\n"
+        res_str += "/\n"
 
-    return ecl_str
+    return res_str
 
 
 def _write_table_records(
@@ -905,7 +905,7 @@ def _write_table_records(
         values_per_line: Number of values per line in output
     """
 
-    ecl_str = ""
+    res_str = ""
     no_records = len(thp_indices)
     no_flow_values = table.size // no_records
     if table.size % no_records > 0:
@@ -918,21 +918,21 @@ def _write_table_records(
         wfr = wfr_indices[row]
         gfr = gfr_indices[row]
         alq = alq_indices[row]
-        ecl_str += f"{thp:2d} {wfr:2d} {gfr:2d} {alq:2d}"
+        res_str += f"{thp:2d} {wfr:2d} {gfr:2d} {alq:2d}"
         for n, value in enumerate(table[row, :]):
-            ecl_str += format % value
+            res_str += format % value
             if (n + 1) % values_per_line == 0:
                 if n < no_flow_values - 1:
-                    ecl_str += "\n"
-                    ecl_str += " " * 11
+                    res_str += "\n"
+                    res_str += " " * 11
                 else:
-                    ecl_str += "\n"
+                    res_str += "\n"
             elif n == no_flow_values - 1:
-                ecl_str += "\n"
+                res_str += "\n"
 
-        ecl_str += "/\n"
+        res_str += "/\n"
 
-    return ecl_str
+    return res_str
 
 
 def df2ecl(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
@@ -957,16 +957,16 @@ def df2ecl(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
     unit_type = vfpprod_data["UNIT_TYPE"]
 
     # Write dataframe to string with Eclipse format for VFPPROD
-    ecl_str = "VFPPROD\n"
+    res_str = "VFPPROD\n"
     if comment:
-        ecl_str += common.comment_formatter(comment)
+        res_str += common.comment_formatter(comment)
     else:
-        ecl_str += "\n"
+        res_str += "\n"
 
     unit_value = vfpprod_data["UNIT_TYPE"].value
     if vfpprod_data["UNIT_TYPE"] == UNITTYPE.DEFAULT:
         unit_value = "1*"
-    ecl_str += _write_basic_record(
+    res_str += _write_basic_record(
         vfpprod_data["TABLE_NUMBER"],
         vfpprod_data["DATUM"],
         vfpprod_data["RATE_TYPE"].value,
@@ -977,37 +977,37 @@ def df2ecl(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
         unit_value,
         vfpprod_data["TAB_TYPE"].value,
     )
-    ecl_str += _write_vfp_range(
+    res_str += _write_vfp_range(
         vfpprod_data["FLOW_VALUES"],
         rate_type.value,
         VFPPROD_UNITS[unit_type.value]["FLO"][rate_type.value],
         "%10.6g",
     )
-    ecl_str += _write_vfp_range(
+    res_str += _write_vfp_range(
         vfpprod_data["THP_VALUES"],
         thp_type.value,
         VFPPROD_UNITS[unit_type.value]["THP"][thp_type.value],
         "%10.6g",
     )
-    ecl_str += _write_vfp_range(
+    res_str += _write_vfp_range(
         vfpprod_data["WFR_VALUES"],
         wfr_type.value,
         VFPPROD_UNITS[unit_type.value]["WFR"][wfr_type.value],
         "%10.6g",
     )
-    ecl_str += _write_vfp_range(
+    res_str += _write_vfp_range(
         vfpprod_data["GFR_VALUES"],
         gfr_type.value,
         VFPPROD_UNITS[unit_type.value]["GFR"][gfr_type.value],
         "%10.6g",
     )
-    ecl_str += _write_vfp_range(
+    res_str += _write_vfp_range(
         vfpprod_data["ALQ_VALUES"],
         alq_type.value,
         VFPPROD_UNITS[unit_type.value]["ALQ"][alq_type.value],
         "%10.6g",
     )
-    ecl_str += _write_table_records(
+    res_str += _write_table_records(
         vfpprod_data["THP_INDICES"],
         vfpprod_data["WFR_INDICES"],
         vfpprod_data["GFR_INDICES"],
@@ -1016,4 +1016,4 @@ def df2ecl(dframe: pd.DataFrame, comment: Optional[str] = None) -> str:
         "%10.6g",
     )
 
-    return ecl_str
+    return res_str
diff --git a/res2df/wellcompletiondata.py b/res2df/wellcompletiondata.py
index d6678e024..921f0c310 100644
--- a/res2df/wellcompletiondata.py
+++ b/res2df/wellcompletiondata.py
@@ -90,7 +90,7 @@ def df(
     return compdat_df
 
 
-def _get_ecl_unit_system(resdatafiles: ResdataFiles) -> EclipseUnitSystem:
+def _get_res_unit_system(resdatafiles: ResdataFiles) -> EclipseUnitSystem:
     """Returns the unit system of an Eclipse input deck. The options are \
     METRIC, FIELD, LAB and PVT-M.
 
@@ -107,7 +107,7 @@ def _get_ecl_unit_system(resdatafiles: ResdataFiles) -> EclipseUnitSystem:
 def _get_metadata(resdatafiles: ResdataFiles) -> Dict[str, Dict[str, Any]]:
     """Provide metadata for the well completion data export"""
     meta: Dict[str, Dict[str, str]] = {}
-    unitsystem = _get_ecl_unit_system(resdatafiles)
+    unitsystem = _get_res_unit_system(resdatafiles)
     kh_units = {
         EclipseUnitSystem.METRIC: KHUnit.METRIC,
         EclipseUnitSystem.FIELD: KHUnit.FIELD,