As far as I am aware there has only been one cannon indication of an actual SIN number, and that was included in Dunkies Will (5T2G-8U6V-PK02). Now the books say that a copper could look at that and determine a fair few things, but I like to think of SINs more as a database referance that pulls up a LoneStar file or some such that includes all that information.
I tried writing up what I imagined a SIN file might look like, but then I got bored half way through and decided against it, this is what I did at the time (But it is just that, something I did when I was bored)
[ Spoiler ]
//LOGFILEDATE – 12/03/70//
//LOGFILETIME – 21.32//
//Connect Host – FDX_LoneStar_Red_SINdatabase2042//
//Request SIN - error file//
//Database Error//
//Send Error Report Y/N?//
//Request SIN – LSO1.H34E.738A//
//Access Granted//
Welcome to LoneStar SIN Database File Number 2042, Officer Grady
//Command.OpenSubfile SIN ARES.D42A.234C//
//Access Granted//
-DECEASED. FILE MARKED 10/21/70
-INVESTIGATION VIEWABLE UNDER HOST FDX_LoneStar_Red_Investigation_Oct2070
SIN FILE – ARES.D42A.234C-DECEASED
SIN IDENTITY – James Mc'Arthur
LEGAL STATUS – Deceased
METATYPE – Dwarf
DOB - 10/21/2043
AWAKENED – N/A
EMERGED – ERRORFILE.ACCESSDENIED //Send Error Report Y/N?//
FATHER – SINID ARES.D24B.642F
MOTHER – SINID ARES.E26A.912M-DECEASED
ACCREDITATION – Graduate Class 2062 MIT&T – Matrix Security and Artificial Sentience Theory – Distinction
WORK HISTORY – Novatech Security Consultant, 2063 - 2064
Ares Macrotechnology Security Consultant, 2065 - 2069
-NOTE ADDED
SIN Identity was present and active during the Matrix Crash Event of 2064. Identity shows possible signs of mental trauma with the potential of AIPS.
For those who are interested I did it like so: First 4 digits show Corporation/Nation the SIN was issued in, 2nd four digits show Metatype and DOB, and then the last 4 are just stuff.