Each TU building is identified by a four-digit building number. The first two digits correspond to the grid square, the last two digits are assigned within each grid square.
The Forum Building, for example, is number 1 within grid square 42 and therefore bears the building number 4201.
The TU site plan with grid squares and building numbers can be found here (please click on the picture):
The abbreviation for the lecture halls and classrooms is composed as follows:
Example: PK 4.3 → Pockelsstr. 4, teaching room No. 3