2.1.873 Part 4 Section 3.14.13, sheetData (External Sheet Data Set)

a.   The standard states that @sheetId index is an unsigned integer, with no additional restrictions on value, and that it is 1-based.

Office requires that @sheetId range from 0 through 65533 inclusive.

b.   The standard does not define any order requirements for rows.

In Office, rows must appear in ascending order.