This is the id of the template document, on google side. You can find it thanks to its URL:

• for a text document with url like `https://docs.google.com/a/openerp.com/document/d/123456789/edit`, the ID is `document:123456789`
• for a spreadsheet document with url like `https://docs.google.com/a/openerp.com/spreadsheet/ccc?key=123456789#gid=0`, the ID is `spreadsheet:123456789`
• for a presentation (slide show) document with url like `https://docs.google.com/a/openerp.com/presentation/d/123456789/edit#slide=id.p`, the ID is `presentation:123456789`
• for a drawing document with url like `https://docs.google.com/a/openerp.com/drawings/d/123456789/edit`, the ID is `drawings:123456789`