Perhaps a bit of history might help.
Barcode verification standards were codified in 1990 through ANSI.
A bit later Applied Image, greif's company, made some of the first barcode calibration standard cards. They were purchased by a variety of companies directly from Applied Image by barcode developers and verification companies and delivered to consumer product manufacturers primarily.
Eventually GS1 started to purchase and resell the cards that AI made and then they private labeled AI cards. Now they make the cards for 2D and linear codes using new 'super verifiers' developed for the purpose.
Today, calibration cards are made by both parties and maybe others. There are a wide variety of cards that are made to suit various purposes. All create and test their cards characteristics using NIST traceable standards. To the best of my knowledge there is no national standard to be used exclusively. I think that the parenthsis was meant to mean 'like GS1' rather than specifying only GS1.
I certainly believe in standards and gage R&R. However, if you are really working on barcode printing systems where you are hoping that this level of precision is going to help bring your grade up above the minimum allowable, then I suggest you step back a bit and look at the big picture. You may need to increase the barcode size to bring up decodeability, increase contrast by using better inks or printing a background, etc. You may even have to step up your game and change to a printing system that is more capable. Todays target is ISO Grade 3-4 which gives you a bit of room for the inevitable goof up.
In many applications that barcode is no longer just another mark. It is data, money, automation, safety, relationships, etc.