I have modified the source modules PROTOCOL.FOR and XMODEM.FOR, along
with the include file PARAMS.INC of Robin Miller's VAXNET program (ver
12.1) to support the XMODEM-CRC protocol.  When sending, CRC usage is
automatic when it is noted that the receiver requests CRC.  When
receiving, an additional prompt is presented to the user after the
RECEIVE command is issued; depending on the users response, VAXNET will
expect CRC. 

The modification was done in a conservative manner:  Rather than create
an additional protocol name, I have modified the low level functions
GET_XMODEM and SEND_XMODEM.  I have also added the subroutine XMODEM_CRC
which I have blatently lifted from the XMODEM_AU program of David
Swanger.  The modification of PROTOCOL.FOR and PARAMS.INC is to send the
required CRC initial character. 

Why did I do it?  I have encountered several BBS systems that don't seem
to want to hear of XMODEM(CHECKSUM) and don't have any form of KERMIT. I
am seriously considering a modification which would increase the maximum
buffer size to 1024 from 128.  On a PC, such a size increase seems to
make a big difference.  On the VAX, I'm not sure, but I may try anyway.