Pedigree records
Important both for understanding your own germplasm, but also for regulatory reasons – often the pedigree of a new variety is required as part of its documentation.
The convention is to place the female parent first: thus AxB (or A/B) means that A was the female parent and B the male.
(AxB)xC (or A/B//C) means that the A x B hybrid was crossed as female to C.
A/B*3 is short-hand for A/B//B///B, ie the A x B hybrid was crossed as female to B, and then this hybrid was crossed as female to B again.