diff --git a/pygmtsar/pygmtsar/Stack_align.py b/pygmtsar/pygmtsar/Stack_align.py
index 8f521f9..ca51949 100644
--- a/pygmtsar/pygmtsar/Stack_align.py
+++ b/pygmtsar/pygmtsar/Stack_align.py
@@ -116,7 +116,7 @@ def _align_ref_subswath(self, subswath, debug=False):
         #print (reference_line)
 
         # for reference scene
-        prefix = self.multistem_stem(subswath)
+        prefix = self.get_subswath_prefix(subswath)
         path_prefix = os.path.join(self.basedir, prefix)
 
         # generate PRM, LED, SLC
@@ -156,7 +156,7 @@ def _align_rep_subswath(self, subswath, date=None, degrees=12.0/3600, debug=Fals
         # temporary filenames to be removed
         cleanup = []
 
-        ref_prefix = self.multistem_stem(subswath)
+        ref_prefix = self.get_subswath_prefix(subswath)
 
         # define reference image parameters
         earth_radius = self.PRM(subswath=subswath).get('earth_radius')
@@ -166,7 +166,7 @@ def _align_rep_subswath(self, subswath, date=None, degrees=12.0/3600, debug=Fals
         topo_llt = self._get_topo_llt(subswath, degrees=degrees)
         #topo_llt.shape
 
-        rep_prefix = self.multistem_stem(subswath, date)
+        rep_prefix = self.get_subswath_prefix(subswath, date)
 
         # define relative filenames for PRM
         rep_prm    = os.path.join(self.basedir, rep_prefix + '.PRM')
@@ -310,7 +310,7 @@ def baseline_table(self, n_jobs=-1, debug=False):
         dates = self.df[self.df.subswath==subswath].date
 
         def get_filename(date):
-            stem = self.multistem_stem(subswath, date)
+            stem = self.get_subswath_prefix(subswath, date)
             filename = os.path.join(self.basedir, f'{stem}.PRM')
             return filename
 
diff --git a/pygmtsar/pygmtsar/Stack_base.py b/pygmtsar/pygmtsar/Stack_base.py
index 7b39214..c388502 100644
--- a/pygmtsar/pygmtsar/Stack_base.py
+++ b/pygmtsar/pygmtsar/Stack_base.py
@@ -31,7 +31,7 @@ def to_dataframe(self):
         """
         return self.df
 
-    def multistem_stem(self, subswath, date=None):
+    def get_subswath_prefix(self, subswath, date=None):
         """
         Define stem and multistem using date  
         """
@@ -41,10 +41,9 @@ def multistem_stem(self, subswath, date=None):
         if date is None:
             date = self.reference
     
-        assert len(date)==10, 'ERROR: multistem_stem date format is not yyyy-mm-dd'
+        assert len(date)==10, 'ERROR: date format is not yyyy-mm-dd'
 
-        prefix = f'{date}_F{subswath}'
-        return prefix
+        return f'{date}_F{subswath}'
 
     def set_reference(self, reference):
         """
diff --git a/pygmtsar/pygmtsar/Stack_prm.py b/pygmtsar/pygmtsar/Stack_prm.py
index 6cf45ee..0a00bcd 100644
--- a/pygmtsar/pygmtsar/Stack_prm.py
+++ b/pygmtsar/pygmtsar/Stack_prm.py
@@ -39,7 +39,7 @@ def PRM(self, date=None, subswath=None):
         if date is None:
             date == self.reference
 
-        prefix = self.multistem_stem(subswath, date)
+        prefix = self.get_subswath_prefix(subswath, date)
         filename = os.path.join(self.basedir, f'{prefix}.PRM')
         return PRM.from_file(filename)
         
diff --git a/pygmtsar/pygmtsar/Stack_reframe.py b/pygmtsar/pygmtsar/Stack_reframe.py
index 23aa993..652c838 100644
--- a/pygmtsar/pygmtsar/Stack_reframe.py
+++ b/pygmtsar/pygmtsar/Stack_reframe.py
@@ -75,7 +75,7 @@ def _reframe_subswath(self, subswath, date, geometry, debug=False):
         df = self.get_repeat(subswath, date)
         if debug:
             print('DEBUG: reframe scenes: ', len(df))
-        prefix = self.multistem_stem(subswath, date)
+        prefix = self.get_subswath_prefix(subswath, date)
         if debug:
             print ('DEBUG: ','prefix', prefix)
 
diff --git a/pygmtsar/pygmtsar/Stack_reframe_gmtsar.py b/pygmtsar/pygmtsar/Stack_reframe_gmtsar.py
index dee08e7..f9dd7e3 100644
--- a/pygmtsar/pygmtsar/Stack_reframe_gmtsar.py
+++ b/pygmtsar/pygmtsar/Stack_reframe_gmtsar.py
@@ -43,7 +43,7 @@ def _ext_orb_s1a(self, subswath, date=None, debug=False):
 
         orbit = os.path.relpath(df['orbitpath'].iloc[0], self.basedir)
 
-        prefix = self.multistem_stem(subswath, date)
+        prefix = self.get_subswath_prefix(subswath, date)
         
         argv = ['ext_orb_s1a', f'{prefix}.PRM', orbit, prefix]
         if debug:
@@ -108,7 +108,7 @@ def _make_s1a_tops(self, subswath, date=None, mode=0, rshift_fromfile=None, ashi
         # TODO: use subswath
         xmlfile = os.path.relpath(df['metapath'].iloc[0], self.basedir)
         datafile = os.path.relpath(df['datapath'].iloc[0], self.basedir)
-        prefix = self.multistem_stem(subswath, date)
+        prefix = self.get_subswath_prefix(subswath, date)
 
         argv = ['make_s1a_tops', xmlfile, datafile, prefix, str(mode)]
         if rshift_fromfile is not None:
@@ -173,7 +173,7 @@ def _assemble_tops(self, subswath, date, azi_1, azi_2, debug=False):
         else:
             datapaths = [os.path.relpath(path, self.basedir)[:-5] for path in df['datapath']]
         #print ('datapaths', datapaths)
-        prefix = self.multistem_stem(subswath, date)
+        prefix = self.get_subswath_prefix(subswath, date)
 
         # round values and convert to strings
         azi_1 = np.round(azi_1).astype(int).astype(str)