Do PSN games have some sort of ID number, like a barcode?

According to this website:

Step 1: Log on to PSN (ON YOUR COMPUTER) for the respective region you wish to find the SKU for(in the US, for example, it's us.playstation.com).

Step 2: After that search for the game you want using the search bar on left side of the screen at the bottom of the buttons. After you have found the page of the game you are looking for, hit control + u to bring up source code of the page.

Step 3: Near the bottom of the source code, you should see something like this:

    <meta name="hasTrailer" content=""/>
    <meta name="gameRating" content="TEEN"/>
    <meta name="partOfGame" content="Prince of Persia® Sands of Time HD"/>

    <meta name="SKU-ID" content="NPUB-30303"/>
    <meta name="last-modified" content="2010-12-27"/>

The second-last line of the source code is the SKU or game id of the game you were looking for (so for instance this would be NPUB30303).

I've also recently noticed that the purchase confirmation emails (sent with every purchase) contain the ID numbers. I don't know why I've never noticed them before (probably because I just mark them as read normally). Since I've kept them all in a PlayStation Network folder on my email account, I can actually go back through some of the games that are no longer listed on the website and find their ID numbers.

UP2054-NPUB30373_00-PS3ST_LIMBO00000-UG02 LIMBO (Full Game)

UP2024-NPUB30381_00-PS3ST_SECT8PREJU-UG03 Section 8(R): Prejudice™ (Full Game)

UP0001-NPUB30163_00-PS3STOREOUTLANDF-UG03 Outland™ (Full Game)

I suppose if you wanted, you could use that massive string as an ID, but for my use the simple npub ID strings suffice.