2.1.1740 Part 4 Section 220.127.116.11, control (Floating Embedded Control)
For additional notes that apply to this portion of the standard, please see the notes for pict, §14.5.1(a) .
a. The standard allows strings of unbounded length for the value of the shapeid attribute.
Word restricts the value of the shapeid attribute to at most 254 characters.
b. The standard specifies that this element is resolved by looking for a DrawingML object whose id attribute matches the value specified by the shapeid attribute.
Word looks for a VML shape element ("[ISO/IEC-29500-4] §18.104.22.168; shape (Shape Definition)"), whose id attribute matches the value specified by the shapeid attribute.