I've gotten far enough along with the Tops-20 finger server that I thought it would be a good idea to capture some of the common assumptions and requirements into a DECnet finger specification document of a sorts.  The current working version can be found at: VENTI2::DECNET-FINGER-SPECIFICATION.TXT.

I emphasize WORKING VERSION as I have been working with (a very patient) Johnny to run tests, and chase down documentation bugs, gaps, inaccuracies and other delusions.  It's an active work in progress.

In particular, the limits of certain connections field are based what is documented in the January 1980 version of the  TOPS-20 DECnet-20 Programmer's Guide and Operations Manual, Order Number AA-5091A-TM.  This is quite old as it is based on Tops-20 version 4 and Tops-20 DECnet version 2.  However, it is what I had handy and what I remember coding to, back in the day.  Connection parameters are partially specified as attributes and are as follows:

• ;USERID:userid where userid consists of 1 to 16 contiguous alphanumeric ASCII characters (including the hyphen, dollar sign, and underscore) identifying the source task. Example: ;USERID:ALIBABA
• ;PASSWORD:password where password consists of 1 to a contiguous alphanumeric ASCII characters (including the hyphen, dollar sign, and underscore) required by the target task to validate the connection. Example: ;PASSWORD:SESAME
• ;CHARGE:acctno  where acctno consists of 1 to 16 contiguous alphanumeric ASCII characters (including the hyphen, dollar sign, and underscore) representing the source task's account identification. Example: ;CHARGE:ACCT-13C
• ;DATA:userdata where userdata consists of 1 to 16 contiguous alphanumeric ASCII characters (including the hyphen, dollar sign, and underscore) representing user data.  Example: ;DATA:THIS-IS-A-TEST

I've since found out that I'm wrong about USERID, and that it actually allows up to 39 characters and have tested this.

What specification has these field definitions and limits?  I'd like to look at it before I go digging into Tops-20 and, of course, fixing the finger server.