The intended usage of prefix words that specify compartments or markings is to specify special inverse bits that allow special inverse words. Special inverse words are words that specify a prefix that in turn specifies compartments or markings. The intended purpose and usage of special inverse bits and special inverse words is best described by the example below.
Special inverse words can be used to implement the ORiginator CONtrolled (ORCON) handling caveat with organizations to which the ORCON data can be released specified in the label. For example, given that three organizations use a particular system (ORG1, ORG@, and ORG3), the encodings to handle ORCON for these three organizations might look as follows. Only the SENSITIVITY LABELS words are shown in this example.
SENSITIVITY LABELS: WORDS: name=ORCON RELEASABLE TO; sname=OR; compartments=1-4; prefix; name=ORCON; minclass=C; compartments=1-4; name=ORG1; minclass=C; compartments=~1 4; prefix=OR; name=ORG2 minclass=C; compartments=~2 4; prefix=OR; name=ORG3; minclass=C; compartments=~3 4; prefix=OR;
In this example, ORG1, ORG2, and ORG3 are special inverse words, each of which requires the prefix ORCON RELEASABLE TO. This prefix specifies compartments bits 1-4, which are therefore special inverse bits. Bit one is for ORG1, bit 2 for ORG2, bit 3 for ORG3, and bit 4 has meaning of ORCON. If only ORCON RELEASABLE TO ORG1 is present in a label, then bit 1 would be off, and bits 2-4 would be on. If only ORG1 is present in a label, then bit 1 would be off, and bits 2-4 would be on. If only ORCON RELEASABLE TO ORG2 is present in a label, then bit 2 would be off, and bits 1, 3, and 4 would be on. If only ORCON RELEASABLE TO ORG3 is present in a label, then bit 3 would be off, and bits 1, 2, and 4 would be on. If ORCON RELEASABLE TO ORG1/ORG2 is present in a label, then bits 1 and 2 would be off and bits 3 and 4 would be on, and so on. The word ORCON, which dominates the three other words, is not an inverse word. If it appears in a label, the data so labeled is not releasable to any of the three organizations.
Note that a label that does not contain any of the above words has bits 1-3 off and is therefore releasable to all organizations, and has bit 4 off and is therefore not ORCON data. Thus, with the same words as above for information labels, data with an information label of SECRET ORCON RELEASABLE TO ORG1 when combined with data with an information label of TOP SECRET, would become TOP SECRET ORCON RELEASEABLE TO ORG1. Special inverse words can be specified using markings bits also.
Unlike regular inverse bits, special inverse bits should not be preallocated to allow for future usage. Special inverse bits can be safely added to a running system without preplanning.