Font Embedding
As well as providing information about the font's metrics, applications may be directed to embed the contents of a font (partially or as a whole) into a document, a process known as font embedding. Font embedding literally embeds an obfuscated version of the font into the file so that it may be retrieved and used to view the contents of this document - but the obfuscation ensures that the font cannot be extracted and used for any other document (as it may have a commercial license).
Within the font table, when a font is embedded there are explicit relationships to each font form needed:
Regular
Bold
Italic
Bold + Italic
Each form is obfuscated using the mechanism described in the reference material on this subject.