[math] Where is the document on development guidelines?

[Disc Magnet]

A few years back when I browsed the Apache Commons Math website, I found a
document describing how boundary cases, overflows, divide by zero, error
conditions, etc. are handled. They were some guidelines meant to be followed
by the developers of Commons Math. I am unable to locate this document now.
Could someone please help? Or is it that the guidelines are no longer
considered necessary?