The provider I saw stuck her tongue in my mouth completely and moved it around rather aggressively.  That was DFK for sure.

I'm just wondering if LFK means just the tips of your/her tongues touching, or does it also mean you can taste the whole length of her tongue but do it gently?  

If she doesn't do DFK, when will she stop you... like if you go maybe half the length down her?

Congress is now holding hearings to determine whether it is the national interest to set standards that would consistantly define a DFK in Alabama the same as a DFK in Nevada.  "My constituants want to know that when he is on the road some Iowa woman won't be stopping his tongue short where a Missouri woman might suck that slimey animal right down her sexy 'Show Me!' gullette" said Missouri congressman Blowhard.  It is rumored that the National Guard may receive special training to assist with lingual border patrol.  "We'll make no arrests, mind you, just make sure FKers know what the rules are."  said General Palettedancer holding station on the newly defined "French" border.  "I'm scirred and staying home till this is all cleared up!" said Newbie Nightseeker, tongue firmly in cheek.

. . . would have to make a ruling as it involves interstate commmerce.

seems like some girls will allow you to stick your tongue in their mouth, but will keep their lips closed so you can only get the tip of their tongue, or they will bring their tongue out but keep the lips mainly closed; to me that's LFK, anything else DFK