The SD File specification is available from MDL Information Systems as part of the CTFile Formats PDF document.
By default, PyMOL supports reading of the MOL block within SD file records. SD files containing multiple structures will be read into PyMOL as objects containing multiple states. The title for each state will be take
In addition, there is an experimental facility for loading SD file annotation into PyMOL. This approach bypasses the fast C-based SD file reader in favor of the more complete Python-based reader.