Known In The SCA (as).
This was a common acronym found in the signature block of many early postings on the old Rialto as well as early e-mail and list servers. It's usage has fallen in recent years.
Example: Joe Binotz KITSCA Ulrich Wordsbane.
The opposite of this is "MKA", or "Mundanely Known As".
Example: Ulrich Wordsbane MKA Joe Binotz.
This may reflect a change in the self-perception of members of the Society. KITSCA may reveal an attitude that the member identifies with their persona as less important than their mundane real-world identity. MKA would seem to give the persona aspect with at least as much, if not more importance than their mundane identity, at least when communicating in SCA-oriented channels.
Note: Is there a category for SCA-specific "culture" or "anthropology" or usages that are not historically based? This subject would fit that category.