Rustic Front seaters flew with XX call sign I.E. Rustic 22
Rustic French Speakers in RCP flew  with Phonetic   I.E. Rustic Yankee etc.
Also in my  era   Nail FCP flew with double digit  I.E. Nail 27
Nail FAN/WSO/Zotters flew with triple digit.. I.E.   Nail 225(also known a Nail two and quarter).. but I believe there were occasions when there were so many Nails that some may have used 1XX..but  I have not run into any yet in the  23D History.