diff --git a/modules/aeolus/datasource.py b/modules/aeolus/datasource.py
index 1f077bf962e1e7c7ebeb18915b8e700d0a77c74f..128b46ad4c0648a643ef9ec54d21941fe10e56e9 100644
--- a/modules/aeolus/datasource.py
+++ b/modules/aeolus/datasource.py
@@ -78,7 +78,16 @@ def get_parameters_fmwk_amvs(filename='/ships19/cloud/scratch/4TH_AMV_INTERCOMPA
 
 
 class Files:
+    """
+    Provides a time-ordered view of a set of files of identical structure and contents but separated by time.
+    """
     def __init__(self, files_path, file_time_span, pattern):
+        """
+        :param files_path: Location of target files, can have wildcard characters.
+        :param file_time_span: Duration of a file (minutes). For example, an 8-minute polar orbiting granule or the
+        time between successive geostationary CONUS products. Assumed to be fixed.
+        :param pattern: The glob pattern that matches the files: concatenated with files_path.
+        """
         self.flist = []
         self.ftimes = []
         self.dto_s = []