Many of the structures written in Word files differ slightly from the corresponding structures Word uses internally. The file-specific version of a structure is typically named by adding a preceding or (more often) trailing F. For example, Word uses internally a PLC (PLex of Cps), but writes to files a PLCF (PLex of Cps in File). Many discussions in this document use the name of the internal structure when the file-specific structure is what is really being referred to. The reader should remember that the name of a seemingly undefined structure type may simply be missing a leading or trailing F.