2.1.1402 Part 4 Section, ST_ShapeID (Shape ID)

a.   The standard does not limit the length of the value of the ST_ShapeID simple type.

Office restricts the value of this simple type to be at most 255 characters.

b.   The standard states that the ST_ShapeID contents are a restriction of the XML Schema token datatype.

In Office, the ST_ShapeID simple type represents an object ID number.  An ID number has the following format characteristics:

Each ID number has a preface of “_x0000_” followed by 1 character and a number, in the general form _x0000_[c]<num>

The character [c] is:

t’ or ‘m’ when used for a shapetype element (“[ECMA-376] Part 4 §; shapetype (Shape Template)”).

s’ when used for a shape.

Shape IDs always start at 1025.

Shape IDs are clustered together, and each cluster has 1024 values.  The   first cluster ranges from 1025 to 2048.

Shape IDs within the same cluster may only exist in:

one worksheet, for Excel.

one slide, for PowerPoint.

one document, for Word.

the header, for Word.

s’ or ‘i’ for shapes that are inline (not floating) in Word.

__<num> must be between 1 and 268435456.

An ID number should not contain any Numeric Character Reference (NCR) markup characters.

Office does not guarantee that the same Object ID number that is loaded is round tripped on file save.