Each files can be decomposed as follow: 
nam0yydddhh_raw.txt

yy is the year (08)
ddd is the Julian Day (68 in this example)
hh is the hour (hour 0 in this case)

nam:
cla = CLASP system from University of Leeds (sea spray measurement)
fos = Fast Ozone Sensor from INSTAAR (ozone flux)
gps = GPS unit
hed = heading system (the one you get your time stamp from)
las = Laser wave sensor Riegl
li1 = Licor paired (#1223)
li2 = Licor paired (#0906)
li3 = Licor solo 
lis = Sample Licor
lin = Null Licor
met = Slow mean data (T/RH, PIR/PSP,...)
mot = Motion Pack
scs = Ship data
son = Sonic data