[nos-bbs] mailbox naming restrictions

[Maiko Langelaar]

If one is using the #define MBX_CALLCHECK feature the minimum is 3
and maximum is 6. For complete rules (I got this from K2MF Barry),
please check the source file callval.c, it documents them.

Otherwise,

> -- Is there a minimum number of characters?

Not NULL.

> -- Is there a maximum number of characters?

Structurely speaking, that would be MBXNAME = 20, the area
name (which one would not login to anyways) is AREALEN = 64
characters. These are defined in mailbox.h header file.

> -- What characters are allowed

Alphanumeric

ALSO : K6FSH had some tactical callsign checks in callval.c as well.

Maiko