The font macros now run smoothly without crashing your document editor.
The "joined" feature means the font is designed to connect letters automatically, simulating cursive handwriting [1]. "1a" Style/Upd: font xccw joined 1a upd
If you use command-line tools like fontmake or ttx (TTX/FontTools), you often get raw status logs. xccw might be the filename prefix. The compiler successfully joined a multi-master font and spat out 1a as a build flag before the upd ate signal. The font macros now run smoothly without crashing