This is a list of agreed design decisions which affect work on BibLaTeX and Biber. It's here so that developers work to what's agreed.
The name of the control file will be <jobname>.bcf
So, assuming a TeX source file with name
example.tex
BibLaTeX would write a control file with name
example.bcf
The control file will be XML. The current working example and schema can be found here.