AT&T 6300 Programmer's Manual page 424

PUT (COM files)
Statement
Writes a specified number of bytes to a
communications file.
Syntax
filenum
length
Example
Remarks
7-268
PUT [#] filenum [,length]
is an integer expression returning a valid file number
is an integer expression returning the number of bytes to be
transferred out of the communications buffer. 'length'
cannot exceed the value set by the IS: switch when GWBASIC
was invoked or the value optionally set in the OPEN
statement.
100 PUT #2, 80
This is ordinarily used only in a program, not
in direct mode.