Glossary
Shell item
A binary structure the Windows shell uses to identify one component of a path, such as a drive, folder, share or Control Panel item.
A shell item (an SHITEMID in Microsoft's documentation) is one element of an item ID list: a 2-byte size, a class type byte at offset 2, and a body whose format depends on the type (root folder GUID, volume letter, file entry, network location, and more). The contents are undocumented by Microsoft; libyal's libfwsi is the reference specification.
Shell items appear in ShellBags, LNK files and Jump Lists. A file entry item can carry the 0xBEEF0004 extension block. See the shell item format explained.