2.2.5.1.1 Least Significant Bit Order

  • Article

Certain tokens will possess rules that comprise an array of independent bits. These are typically "flag" rules in which each bit is a flag indicating that a specific feature or option is enabled/requested. Normally, the bit array will be arranged in least significant bit order (or typical array index order) meaning that the first listed flag is placed in the least significant bit position (identifying the least significant bit as one would in an integer variable). For example, if Fn is the nth flag, then the following rule definition:

 FLAGRULE = F0 F1 F2 F3 F4 F5 F6 F7

would be observed on the wire in the natural value order F7F6F5F4F3F2F1F0.

If the rule contains 16 bits, then the order of the bits observed on the wire will follow the little-endian byte ordering. For example, the following rule definition:

 FLAGRULE = F0 F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12 F13 F14 F15

will have the following order on the wire: F7F6F5F4F3F2F1F0 F15F14F13F12F11F10F9F8.