These are the notes for GoZync 3. Docs for the latest version of GoZync--GoZync 4--can be found here. GoZync 4 is a free upgrade and is highly recommended (hint: it's faster).
Yes, By default GoZync will push any records that have been changed since the last sync. If there is one 1 such record you want to sync, you can use the script "Zync It - This Record ( RecordID )" to send just that one record. (This is one of the scripts you import into your file when integrating GoZync; read that script's comments for more.)
But what if you want to send just "some" of the records changed since the last sync? For example, you're making orders in the field and have started several, but only finished about ten of them. You don't want to have to manually sync those 10, one by one using "Zync It - This Record ( RecordID )". You'd rather mark those records as "ready" and just sync the "ready" records.
This is easily done by changing a few fields in your mobile file. Backup your files and then watch this.
You can even go further an make a new copy of gz_send based on the original auto-enter calc, and use that just to indicated if a record has been edited since the last sync. That way you can base "modified" on that new field making it pretty easy to scan the "modified" records and flag some of them as "ready to send".