Looking for schematic of core variable declarations, dependencies, definitions..

I posted a question about the title-tag creation some days ago, which in itself might be sufficiently solved. But on second thoughts I’m indeed even more interested in pieces of information of a more general form.

My general question is about the wordpess core’s variables’ documentation, definitions, declarations and dependencies: These details seem to me to be missing in the documentation, not only for the title variable, but in general. Are there flow chart, or similiar things?

For example for the title-tag in the head section of a final html-page: Which variables are involved in the title-tag creation, where are they declared first, what rules have to or should plugins or direct inserts in the php code follow to not destroy the schematic flow of wordpress (the schematic on which other plugins may rely)?