Binary package “nx-x11proto-damage-dev” in ubuntu focal

nx-X11 Damage extension wire protocol

 NX is a software suite which implements very efficient
 compression of the X11 protocol. This increases performance when
 using X applications over a network, especially a slow one.
 .
 This package provides development headers describing the wire protocol
 for the Damage extension, used to notify clients of changes made to
 particular areas.