mobile_carrot:
I realise that all my WORD documents default to docx format, I thought this was something you had to choose! What would be preferable from my alternatives - "plain text" or "WORD 97-2003" or something else?
The Microsoft .docx format, although supposedly offering advantages, was not compatible with those using earlier versions of Word and in addition, caused issues when being imported into other non-Microsoft word processors. Flopsy and I both use the Linux operating system (rather than Microsoft) and tend to use LibreOffice or, where unavoidable, I run an old version of Windows with an old version of Word as a virtual machine.
All you need to do, however, if using a recent version of Word which defaults to .docx is to select "Save As" instead of Save and select Word 97-2003 or whatever else shows as having a .doc extension (assuming this information isn't hidden in the latest version of Windows). You can of course keep your own version in .docx, it's just the version for us that we need in .doc.
We do, of course, also accept documents in rtf (rich text format), odt (open document text) and plain text too.