Configuring Registers in ARM Cortex M3
My experience is that a lot of manufacturers have bad or no manuals for their include files. They often have a plethora of example programs which use those structures.

Modern GUI's have support to pop-up a list of all the substructures. Below an example screenshot.



But that does not help unless you know the 'magic start runes' (PIOA in this case). Even then you might not know what "PIO_ABCDSR" does. (See my remark about data sheets further) Lately I have been looking more and more at the includes files. In the beginning it is a bit of work to locate the appropriate files but I found that in the end it is faster then looking on the internet, the example programs or the manuals. 

I do have the datasheet next to my keyboard as the register and field names in there often (but not always!)  correspond with the names used in the header files.