All metadata is recorded within the TIFF files in the XMP section. XMP is an XML based metadata format defined by Adobe; you can read the whole specification here, but unless you are trying to write your own parser for the format you should not have to. In XMP, all properties are stored with a name as well as a value allowing human readable identification.
There are some open source libraries you can use to extract the metadata. Two of the more commonly used ones are exiv2 and exiftool. Both of these offer command line utilities that let you quickly extract metadata from a file; exiv2 also has a C++ library you can use in your own software. There are also wrappers for other languages like python.