I found the manual MD110_1023669.pdf on Ericsson's website which says MD110 supports the open QSIG signaling protocol standard. However, when I got the corresponding ECMA/ISO standard following the instruction of this manual, I found there is no detailed description on the QSIG message structure. I wonder if these message structures conform to the standard defined by themselves or the unified standard? Where can I find detailed information about them?