Understanding the GSM specs

[Nordin]

Well guys,

If someone can help me with how to fill in the Rest Octets, I'll send 
you a postcard from my city to thank you :)
What I found out is that it uses CSN.1 notation, but the description is 
hard to follow, I began to see words floating around the screen.

<SI3RestOctet>::=<Optionalselectionparameters>
            <OptionalPoweroffset>
            <SystemInformation2terIndicator>
            <EarlyClassmarkSendingControl>
            <Schedulingifandwhere>
            {L|H<GPRSIndicator>}
            <sparepadding>:

    <OptionalSelectionParameters>::=   L |H <SelectionParameters>;

    <SelectionParameters>::=
            <CBQ:bit(1)>
            <CELL_RESELECT_OFFSET:bit(6)>
            <TEMPORARY_OFFSET:bit(3)>
            <PENALTY_TIME:bit(5)>;

    <OptionalPowerOffset>::=        L |H 
<PowerOffset:bit(2)>;<SystemInformation2terIndicator>::=
        L|H;

    <EarlyClassmarkSendingControl>::= L|H;

    <Schedulingifandwhere>::= L|H <WHERE:bit(3)>;

    <GPRSIndicator>::=        <RACOLOUR :bit(3)>
                                            < SI13POSITION :bit>;

So, now I want to enable GPRS support by do something with 
GPRSIndicator. This is how I thought to do that:
L|H -> 1
next -> RACOLOUR -> 000
next -> SI13POSITION -> 0
So we get -> 1 000 0

Next step is to do something with padding but than I'm lost. I don't 
have good documentations on how to use CSN.1 for GSM network.