How to convert Google spreadsheet's worksheet string id to integer index (GID)?

To export google spreadsheet's single worksheet to CSV, integer worksheet index(GID) is required to be passed.

https://spreadsheets.google.com/feeds/download/spreadsheets/Export?key=%s&gid=%d&exportFormat=csv

But, where are those informations? With gdata.spreadsheets.client, I could find some string id for worksheet like "oc6, ocv, odf".

client = gdata.spreadsheets.client.SpreadsheetsClient()
feed = client.GetWorksheets(spreadsheet, auth_token=auth_token)

And it returns below atom XML. (part of it)

<entry gd:etag="&quot;URJFCB1NQSt7ImBoXhU.&quot;">
    <id>https://spreadsheets.google.com/feeds/worksheets/0AvhN_YU3r5e9dGpTWGx3UVU3MTczaXJuNEFKQjMwN2c/ocw</id>
    <updated>2012-06-21T08:19:46.587Z</updated>
    <app:edited xmlns:app="http://www.w3.org/2007/app">2012-06-21T08:19:46.587Z</app:edited>
    <category scheme="http://schemas.google.com/spreadsheets/2006" term="http://schemas.google.com/spreadsheets/2006#worksheet"/>
    <title>AchievementType</title>
    <content type="application/atom+xml;type=feed" src="https://spreadsheets.google.com/feeds/list/0AvhN_YU3r5e9dGpTWGx3UVU3MTczaXJuNEFKQjMwN2c/ocw/private/full"/>
    <link rel="http://schemas.google.com/spreadsheets/2006#cellsfeed" type="application/atom+xml" href="https://spreadsheets.google.com/feeds/cells/0AvhN_YU3r5e9dGpTWGx3UVU3MTczaXJuNEFKQjMwN2c/ocw/private/full"/>
    <link rel="http://schemas.google.com/visualization/2008#visualizationApi" type="application/atom+xml" href="https://spreadsheets.google.com/tq?key=0AvhN_YU3r5e9dGpTWGx3UVU3MTczaXJuNEFKQjMwN2c&amp;sheet=ocw"/>
    <link rel="self" type="application/atom+xml" href="https://spreadsheets.google.com/feeds/worksheets/0AvhN_YU3r5e9dGpTWGx3UVU3MTczaXJuNEFKQjMwN2c/private/full/ocw"/>
    <link rel="edit" type="application/atom+xml" href="https://spreadsheets.google.com/feeds/worksheets/0AvhN_YU3r5e9dGpTWGx3UVU3MTczaXJuNEFKQjMwN2c/private/full/ocw"/>
    <gs:rowCount>280</gs:rowCount>
    <gs:colCount>28</gs:colCount>
</entry>

Also I tried with sheet parameter but failed with "Invalid Sheet" error.

https://spreadsheets.google.com/feeds/download/spreadsheets/Export?key=%s&sheet=XXX&exportFormat=csv

I guess there should be some magic function but could not find it. How can I convert them to integer id?? Or Can I export worksheet with string id?

EDIT: I just made convert table with python. DIRTY but working :-(

GID_TABLE = {
    'od6': 0, 
    'od7': 1, 
    'od4': 2, 
    'od5': 3, 
    'oda': 4, 
    'odb': 5, 
    'od8': 6, 
    'od9': 7, 
    'ocy': 8, 
    'ocz': 9, 
    'ocw': 10, 
    'ocx': 11, 
    'od2': 12, 
    'od3': 13, 
    'od0': 14, 
    'od1': 15, 
    'ocq': 16, 
    'ocr': 17, 
    'oco': 18, 
    'ocp': 19, 
    'ocu': 20, 
    'ocv': 21, 
    'ocs': 22, 
    'oct': 23, 
    'oci': 24, 
    'ocj': 25, 
    'ocg': 26, 
    'och': 27, 
    'ocm': 28, 
    'ocn': 29, 
    'ock': 30, 
    'ocl': 31, 
    'oe2': 32, 
    'oe3': 33, 
    'oe0': 34, 
    'oe1': 35, 
    'oe6': 36, 
    'oe7': 37, 
    'oe4': 38, 
    'oe5': 39, 
    'odu': 40, 
    'odv': 41, 
    'ods': 42, 
    'odt': 43, 
    'ody': 44, 
    'odz': 45, 
    'odw': 46, 
    'odx': 47, 
    'odm': 48, 
    'odn': 49, 
    'odk': 50, 
    'odl': 51, 
    'odq': 52, 
    'odr': 53, 
    'odo': 54, 
    'odp': 55, 
    'ode': 56, 
    'odf': 57, 
    'odc': 58, 
    'odd': 59, 
    'odi': 60, 
    'odj': 61, 
    'odg': 62, 
    'odh': 63, 
    'obe': 64, 
    'obf': 65, 
    'obc': 66, 
    'obd': 67, 
    'obi': 68, 
    'obj': 69, 
    'obg': 70, 
    'obh': 71, 
    'ob6': 72, 
    'ob7': 73, 
    'ob4': 74, 
    'ob5': 75, 
    'oba': 76, 
    'obb': 77, 
    'ob8': 78, 
    'ob9': 79, 
    'oay': 80, 
    'oaz': 81, 
    'oaw': 82, 
    'oax': 83, 
    'ob2': 84, 
    'ob3': 85, 
    'ob0': 86, 
    'ob1': 87, 
    'oaq': 88, 
    'oar': 89, 
    'oao': 90, 
    'oap': 91, 
    'oau': 92, 
    'oav': 93, 
    'oas': 94, 
    'oat': 95, 
    'oca': 96, 
    'ocb': 97, 
    'oc8': 98, 
    'oc9': 99
}

I found your question looking for a solution to the same problem, and was surprised that those worksheet IDs actually correspond 1:1 to gids - I originally assumed they were assigned independently, instead of being an exercise in obfuscation.

I was able to find a slightly cleaner solution by reverse-engineering the formula they use to generate worksheet IDs from your table:

worksheetID = (gid xor 31578) encoded in base 36

So, some Python to go from a worksheet ID to gid:

def to_gid(worksheet_id):
    return int(worksheet_id, 36) ^ 31578

This is still dirty, but will work for GIDs higher than 99 without requiring giant tables. At least as long as they don't change the generation logic (which they probably won't, as it would break existing IDs that people already use).