shmop_read and write...what is offset?

[sneakyimp]

hi all:

i am considering using the SHMOP functions in PHP....the shmop_read and shmop_write require an integer (the documentation calls it 'offset' for shmop_write and 'start' for shmop_read). what is this value? i'm guessing it's the number of bytes you skip to get to your data item, but i just want to be sure.

j