>What's up with the m.? Why is it there? (Why) should I use it?
This comes from the history of FoxPro (from the xBase days). As Hilmar shows, it allows the program to make a distinction between variables and field names that share the same name (not a good design generally).
"Once again, we come to the Holiday Season, a deeply religious time that each of us observes, in his own way, by going to the mall of his choice." -- Dave Barry