constant measurments??

It's too bad the OP has returned to soak up some of this knowledge. I think he's going to need it.

Well, whilst he is away, I think I can shed some light on some of the other points that were puzzling him.

B stands for breadth. The same thing as width, but with a few extra letters and so is not so popular.

W stands for wire mesh (which you would expect in the middle of a ground slab).

In the designation W/BRC.A142, the W is wire mesh, BRC is the name of a company and A142 is the code for a certain size of mesh spacing.

I thought that re-bar referred to all types of bar that were embedded in concrete, and not specifically high yield steel deformed reinforcing bars, but it has been a few years since I was on site.

I am not sure what else was puzzling him, but it may have more to do with Civil Engineering rather than AutoCAD.

The OP did not know what the letter designations meant but thanks to a number of knowledgeable forum members (I do not count myself in that group) he's been given a wealth of information.

The other thing he did not understand was that he was looking at concrete construction with steel reinforcement. References to ground and floor beams confused him. He thought they might be made of wood.