[TYPO3-english] Explanation of Typo3 database fields

[TDJ]

I have been asked to do a front-end to Typo3 (in Visual Basic or MS Access, 
for simplicity and speed of data entry).

The insertion of the records in the Typo3 database works. But I am 
wondering: is the standard tables / fields in a Typo3 installation 
documented anywhere ? I am thinking about the relation between TCA and the 
content in the database, f.ex. that uid=unique ID for the list / page, 
pid=it's parent. fe_user=who has access. Etc etc.

I tried the API, and looking at documentation, but apparently the best shot 
for me so far has been to dig in PHP source code.

Such documentation would probably also make extending Typo3 simpler, since 
it becomes apparent where to extend.

Hope the question is understandable.