LFILORIGIN sentence in IGC file?

A user of my new IGC logger Excel spreadsheet sent me a pair of IGC files that were clearly duplicates *except* that the first few B records of one file contained clearly bogus GPS locations (displaced a few thousand miles due east!). Naturally, this caused the dupe detection routine (which compares the first B records of each file) to fail.

While investigating the issue, I discovered that the GPS location was corrected a few seconds into the flight, and the location shift was marked by a pair of 'LFILORIGIN' sentences, as follows:

B1742333600000N13600000EV0005300000000
B1742383600000N13600000EV0005300000000
LFILORIGIN1740383600000N13600000E
LFILORIGIN1742432824200N08150270W
B1742432824200N08150270WA0005300049000


I did some Googling for 'LFILORIGIN' and 'LFIL' and anything else I could think of, all to no avail.

Anyone have any documentation on this sentence?

TIA,

Frank (TA)