First stab at a functional description.

functional_description.markdown

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+# General
+
+An SNMP plugin which can take a *gapit config* as input, as oppsosed 
+to manually specifiying OIDs.
+
+Parse/use gapit SNMP config, and snmp get all OIDs listed in config. 
+By default, stop querying OIDs for which "does not exist" is returned. 
+Results are returned in a similar format to the input format, e.g. 
+with group/stat names, and adjusted for specified scaling factors.
+
+# Setup (node edit dialog)
+
+* Same options as general snmp (server, community, etc.).
+* A JSON text field for pasting a gapit config.
+* Alternatively, the gapit config can be passed in the msg object, 
+ overriding the text field (msg.gapit_config).
+* A checkbox for "Keep querying non-existing OIDs" (also with a 
+ msg.requery_nonexisting_oids).
+
+# Internals
+
+Keep track of OID avilability (i.e. which nodes return data, and which 
+return "OID does not exist") in *node context*. Unless "Keep quierying" 
+is set, stop querying unavailable OIDs. (This option is to account for 
+instances where OIDs are ephemeral.)
+