Re: Changing Product ID's[ Edited ]
May 2015 - last edited May 2015
generally, never, ever, change an item's id value
unless directed to do so by a person at google.
the id may be just about any alpha-numeric value you wish --
id must simply be unique per item and should never change;
there are no format requirements for the id attribute.
a best-practice is to use an internal sku or similar --
that includes letters, numbers, and a country code;
e.g. abc123uk, def456uk, redwagon001uk, etc.
how to change an id is like changing any other attribute value --
the details depend on how the feed is created and maintained;
e.g. if a spreadsheet is used, simply edit the spreadsheet and
change the values under the column labeled id