>Familiar with it. Upper bytes for maker of card, lower bytes the auto-increment :^)
>number of the card, or something like that.
Yes, that's right. 3 bytes (or 6 hex digits, since it is usually written in hex) identify the organization.
Difference in opinions hath cost many millions of lives: for instance, whether flesh be bread, or bread be flesh; whether whistling be a vice or a virtue; whether it be better to kiss a post, or throw it into the fire... (from Gulliver's Travels)
