The cGpsMapper manual is an invaluable resource for those constructing or editing .mp ("Polish format") mapping files but the links I found all pointed to the cgpsmapper.com server which seems no longer available. Finally I found an archived version which greatly helped me, so for others having problems accessing the manual a "wayback machine" link is
https://web.archive.org/web/20160729043418/http://cgpsmapper.com/manual.htm
Jack