copyright

支持X/YModem和cis_b+协议的串口通讯程序

XC and its source files and sample scripts and manual page are Copyright
1993 by Jean-Pierre Radley.

Permission is granted to the public to use this code in any manner, without
any warranty, implied or otherwise, of fitness for a particular purpose.

By virtue of a restriction previously placed upon all code derivative from
XCOMM, the XC code and associated files may not be sold by anyone to anyone,
nor incorporated into any product that is not also free. It's OK to transfer
them for free.