Word has three kinds of controls:
• formfields, which work in all Word versions and on all Word platforms;
• ActiveX controls, which only work on PCs; and
• content controls, which only work on PCs & Macs using Word 2007 & later.
To access formfields or ActiveX controls, use the 'Legacy Tools' button in the Controls group of the Developer tab on the Ribbon.

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Cheers,
Paul Edstein
[Fmr MS MVP - Word]