What document contains the official numerical values for JPEG tags?

Question

I know that the official specification for the JPEG file structure can be found at https://www.w3.org/Graphics/JPEG/jfif3.pdf but this doesn't include numerical definitions of the constants used in the specification. It only references the constants when describing structures. For example, at the start of every JPEG file it says is "X’FF’, SOI" where X'FF' means hexadecimal value FF (decimal value 255), followed by the constant called SOI. However, the document does not state what the numerical value of that constant should be. By reverse engineering it (loading a JPEG file into a hex editor) I can see that the value for the SOI constant is hexadecimal value D8, but that is NOT included in the publicly available official specification. Is the public specification only a partial specification? Do you need to pay money to the JPEG inventors to buy a copy of the "full specification" or something, to actually get a document that defines the numerical values for all the constants that are referenced in the specification? There's LOTS of other similar constants that I can't find identified in the tiny publicly available documentation, such as the numerical values for the constants APP0, APP1, APP2, EOI, and many others. Any help locating a more complete official document (I don't want a list of values somebody got from reverse engineering JPEG files), would be greatly appreciated.