Implement 2nd pass.

MEMBERS.md

@@ -46,6 +46,20 @@ value for the key.
 The result of parsing is a list of parsed records containing key,
 value and line number for further processing.
 
+Member File Processing - Pass 2
+-------------------------------
+
+Processed source is scanned for known keys.
+
+Multiple instances of single key are considered an error.
+
+Unknown keys are considered a warning.
+
+Valid multikeys are converted to single key with list of values and
+line numbers as the value for such key.
+
+The result is a valid dictionary of keys and multikeys.
+
 Member File Grammar
 -------------------