VP address register

This is a simple question.

In a ARBvp, I want to use the address register to address some data. The data is in the constant registers (program.env)

This for example doesnt work. GL flags an error because of program.env[A0]:
TEMP r0;
MUL r0, program.env[A0], r0;

That’s a little weird. Aren’t the constants in an array (or like an array)?

This works fine

PARAM array[4]={program.env[8…11]};
MUL r0, array[A0], r0;

What’s the point of having PARAM array[4]={program.env[8…11]}?

For some reason they don’t allow direct PARAM use, you have to “bind” it to a name.

It is kind of odd though, that you can use all the other vars (ATTRIB, OUTPUT) with out binding them to a name.

There are small details like this that the spec doesn’t explain.

Of course, there are examples that show you what to do.