robsterUK What the note is probably referring to is an option for File Upload fields that appeared in Machform versions prior to 16. This was a check box with the text "Enable Advanced Uploader", which checked by default for all File Upload fields. This option presumably has been removed in Machform 16. (I cannot say this for sure because I haven't upgraded to Machform 16 yet.) Unchecking this box produces (in versions of Machform prior to 16) a File Upload field that only allows one file to be uploaded at a time.
So, if I am correct, it is not that any new file uploading functionality was introduced in Machform 16, just that an option to revert to an older, less "advanced" type of File Upload was removed.
Please note that I do not work for Machform and have no responsibility for nor power to change any ambiguity or lack of clarity that may exist in the release notes.