x11proto-core-dev 7.0.28-0ubuntu2 (s390x binary) in ubuntu xenial

 This package provides development headers describing the wire protocol
 for the core X11 protocol, and also provides a number of utility headers,
 used to abstract OS-specific functions.
 .
 More information about X.Org can be found at:
 <URL:http://www.X.org>
 .
 This package is built from the X.org xproto proto module.