LP siding as roof deck

This is a first for me. The builder (probably an owner-builder) used what appears to be LP siding panels (OSB with signature knot) to construct the roof deck. The home has vaulted ceilings throughout, so the LP was only visible at the soffits and above the front porch. There was plenty of rot and excessive moisture, especially at the edges. My question is: Did LP ever manufacture an APA span rated OSB product that looks like sheet siding? I would like confirmation that, in addition to the performance issues, it is impoper to use a non span rated sheet good at the roof deck. Sorry for no photos, they all turned out bad. This is a 1994-95 home.