The 48 and 49 you are talking about Airgus is the depth of deposit from a snowtam. These figures relate to the depth of the contaminant.
48mm/49mm. Those figures go up to a value of 90, then 92 equates to 100mm, 93 150mm all the way up to 98 which is 400mm.
99 means that the R/W is not operational because of the depth of the contaminate or R/W clearance is in progress.
Oz