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. Its usage has fallen in recent years.
Example: Joe Binotz KITSCA Ulrich Wordsbane.
Example: Ulrich Wordsbane MKA Joe Binotz.
This may reflect a difference in how some members of the Society view their persona relative to their real-world identity. "KITSCA" may reveal an attitude wherein the member considers their persona to be less important than their mundane real-world identity. The use of "MKA" would seem to credit one's persona with at least as much if not more importance than their mundane identity, at least when communicating in SCA-oriented channels.