floppy low level format question

Hmm, my pondering about reading raw data from floppies got me thinking. I have some data on low level floppy format, which gives the following information: Each track has an index gap, followed by a gap 1, followed by a number of sectors, followed by a termination gap. Each sector is made up of an ID field, seperator gap, data field, and then a trailing gap on all except the last sector on a track. This is given as the same for both MFM and FM recording. The information I have gives the makeup of each of the gap types in terms of bit patterns, counts, what clock transitions are missing for MFM formats etc. Question is, is this a standard? I mean, for any disk using MFM or FM recording are these bit patterns going to be the same? Or is it dependant on the controller chip being used? cheers Jules