Because it has been released on the 50th week of 2007 (that makes the 2007.50 part. So as far as I know: RX-34_2008SE_2.2007.50-2_PR_COMBINED_MR0_ARM.bin RX-34 is the N800 tablet (RX-44 the N810). 2008SE is the OS edition _2 is the release version (_1 was the Beta) 2007.50 is the week it was released -2 should be some internal versioning about the package _PR_COMBINED_MR0 should be related to the hardware arch _ARM is the processor architecture .bin because it's in binary format.