2.1.459 Part 1 Section 17.16.4.3, General formatting

a.   The standard makes no mention of the MERGEFORMATINET switch argument

Word understands an additional switch argument, MERGEFORMATINET.

When this switch argument is present on an INCLUDEPICTURE or IMPORT field, Word will preserve the dimensions of any picture within the result such that when the result is updated with a new picture, the dimensions of the new picture shall be set to match the dimensions of the original picture.

When this switch argument is present on any other field, Word interprets this the same as a MERGEFORMAT switch.