2.2.1 Header

An SPV light member begins with a 39-byte header:

Header =>
    01 00
    (i1 | i3)[version]
    bool[x0]
    bool[x1]
    bool[rotate-inner-column-labels]
    bool[rotate-outer-row-labels]
    bool[x2]
    int32[x3]
    int32[min-col-width] int32[max-col-width]
    int32[min-row-width] int32[max-row-width]
    int64[table-id]

version is a version number that affects the interpretation of some of the other data in the member. We will refer to “version 1” and “version 3” later on and use v1(…) and v3(…) for version-specific formatting (as described previously).

If rotate-inner-column-labels is 1, then column labels closest to the data are rotated 90° counterclockwise; otherwise, they are shown in the normal way.

If rotate-outer-row-labels is 1, then row labels farthest from the data are rotated 90° counterclockwise; otherwise, they are shown in the normal way.

min-col-width is the minimum width that a column will be assigned automatically. max-col-width is the maximum width that a column will be assigned to accommodate a long column label. min-row-width and max-row-width are a similar range for the width of row labels. All of these measurements are in 1/96 inch units (called a “device independent pixel” unit in Windows).

table-id is a binary version of the tableId attribute in the structure member that refers to the detail member. For example, if tableId is -4122591256483201023, then table-id would be 0xc6c99d183b300001.

The meaning of the other variable parts of the header is not known. A writer may safely use version 3, true for x0, false for x1, true for x2, and 0x15 for x3.