The 0-0 paint code (or 0-1 (2 or 4) for convertibles) was a special paint instruction code for the 67s in the PNT area of the cowl tag. The - - - for 68 and - - for 69 (all could have a letter code in the last dash for a vinyl or convertible top color) were special paint instruction codes for 68 and 69. Note the word instruction. The code didn't tell the assemblers anything about what color, or if it was a stripe deletion, or if it was going to receive a show finsh, it was just a code to clue the FISHER paint line that there were special paint requirments for this car. The actual requirements were on a peice of paper that accompanied the car, or were on hand at the paint booth. The - or - and a number at the bottom of the tag were indicative of an FSO (fleet or Special Order) number. The two have nothing to do with each other, unless the FSO had a special order or show finish paint associated with it, in which case you would have 0's or -'s in the PNT section and an FSO number at the bottom.
If you think GM cared about either dash on the tag, and used it to delete stripes, or paint a stripe a different color, or even paint the front end a non standard color then your going to have to explain to me how they saw the tag when the rear half of the car was on the Trim engine or Chassis assembly line when the Front sheetmetal was being painted in the paint booth in two separate areas of the plant. The first time the front end sheetmetal came together with the body tub was in the final assembly line after the engine and running rear was already installed. They did it with the Body Broadcast sheets. My opinion, not documented fact.