Hi Darkwander
You mean a number field not text?

Adding fields is a long job if you want to cover all the admin icon functions on right of an admin product list such as 'product copy'.

Personally I'd find an existing unwanted field of similar field type and rename it on the admin pages templates, and in product display.

Or you just sit there and find ALL the pages of that product type which process a particular field, and add in your own one. But there are places where an array pre-sets the possible field names used further down the code, so they have to have added entries as well.

Mind you it is how I added fields to the book product and its worth adding extra ones because you WILL suddenly decide later after doing it all, to add some more, by which time you forget what to do.. ::frust and then want to shoot yourself