diff --git a/pycmx/edit_list.py b/pycmx/edit_list.py
index 490358c..ae9d774 100644
--- a/pycmx/edit_list.py
+++ b/pycmx/edit_list.py
@@ -32,11 +32,11 @@ class EditList:
             (s for s in self.event_statements if type(s) is StmtEvent), None)
 
         if first_event:
-            if first_event.format == 8:
+            if first_event.source_field_size == 8:
                 return '3600'
-            elif first_event.format == 32:
+            elif first_event.source_field_size == 32:
                 return 'File32'
-            elif first_event.format == 128:
+            elif first_event.source_field_size == 128:
                 return 'File128'
             else:
                 return 'unknown'
diff --git a/pycmx/parse_cmx_statements.py b/pycmx/parse_cmx_statements.py
index 5cb7fb5..000426c 100644
--- a/pycmx/parse_cmx_statements.py
+++ b/pycmx/parse_cmx_statements.py
@@ -192,7 +192,7 @@ def _parse_columns_for_standard_form(line: str, event_field_length: int,
                      source_out=column_strings[12].strip(),
                      record_in=column_strings[14].strip(),
                      record_out=column_strings[16].strip(),
-                     line_number=line_number, format=source_field_length)
+                     line_number=line_number, source_field_size=source_field_length)
 
 
 def _parse_source_umid_statement(line, line_number):
diff --git a/pycmx/statements.py b/pycmx/statements.py
index 2a269f4..7a75584 100644
--- a/pycmx/statements.py
+++ b/pycmx/statements.py
@@ -23,7 +23,7 @@ class StmtEvent(NamedTuple):
     source_out: str
     record_in: str
     record_out: str
-    format: int
+    source_field_size: int
     line_number: int