Manpages of src:leptonlib in Debian stretch-backports

• convertfilestopdf(1)
• convertfilestops(1)
• convertformat(1)
• convertsegfilestopdf(1)
• convertsegfilestops(1)
• converttopdf(1)
• converttops(1)
• fileinfo(1)
• leptonica(3)
• xtractprotos(1)