More of member-record documentation.

MODULES.md

@@ -98,6 +98,28 @@ Known types are:
 
 The structure is perfectly suited for ```print-source-listing``` function.
 
+    (member-sub-ref mr sec key [default])
+
+* ```mr``` - a member record structure
+* ```sec``` - section symbol
+* ```key``` - key symbol
+* ```default``` - optional default value
+
+Retrieves given ```key``` from dictionary stored as section ```sec```
+in given ```mr``` structure. If no ```default``` is provided and the
+```key``` does not exist it raises an exception.
+
+    (member-sub-set mr sec key value)
+
+* ```mr``` - a member record structure
+* ```sec``` - section symbol
+* ```key``` - key symbol
+* ```value``` - value to set
+
+Sets the value of given ```key``` in dictionary stored as section
+```sec``` in given ```mr``` structure to the new ```value``` possibly
+overwriting previous one.
+
 ### Member Parser
 
 ### Members Directory