The establishment of hierarchies among words is an extremely important feature of the translation software, because the software enforces that two words in the same hierarchy cannot appear together in a label. The software infers a hierarchy between two words W1 and W2 whenever both of the following two conditions are true: 1) if the bits explicitly specified for W1 includes all of the bits explicitly specified for W2, and 2) if the values of the bits specified for W1 dominates the values of the same bits for W2, with unspecified bits in W2 taken to be 0. The following series of examples highlights these concepts.
Example 8-3 shows the encoding of two normal words in a hierarchy, with word5 hierarchically above word4. This is the most common way to encode a hierarchy of normal words, with 1) the words in decreasing hierarchical order and 2) without any 0 bits explicitly encoded (using a ~). It is unnecessary to explicitly specify that for word4 bit 4 must be 0 (using ~4) because bit 4 was not specified as 1 in the initial marking bits. Note that if bit 4 is not specified as 0 for word4, that word4 must appear after word5 in the encodings. If the order of the two words were reversed, a label with bits 3 and 4 as 1 would have word4 shown in the human-readable label, because although both the word4 and word5 bits match the internal format, word4 would be encountered first by the translation software.
Example 8-3 Two Normal Words in a Hierarchy
name= word5; markings= 3 4; name= word4; markings= 3;
Example 8-4 is identical to the above example, except it demonstrates that while the ~4 is not necessary, it is a valid alternative representation. Note that bit 4 is not an inverse bit, and therefore need not be specified as 1 in the initial marking bits.
Example 8-4 Normal Words Alternative Representation
name= word5; markings= 3 4; name= word4; markings= 3 ~4;
Example 8-5 is identical to the above example, but has the order of the words reversed. This example works properly because the ~4 is present. As above, note that bit 4 is not an inverse bit, and therefore need not be specified as 1 in the initial marking bits.
Example 8-5 Normal Words Reversed Order
name= word4; markings= 3 ~4; name= word5; markings= 3 4;
Example 8-6 shows a hierarchy of inverse words, with word12 above word13 in the hierarchy. In this example, both bits 3 and 4 are inverse bits, and are specified as 1 in the initial marking bits.
Example 8-6 Hierarchy of Inverse Words
name= word12; markings= 3 ~4; name= word13; markings= ~3 ~4;
Example 8-7 does not represent any hierarchy between the two words. Bit 4 is an inverse bit, and is specified as 1 in the initial marking bits. Word12 is not in a hierarchy above word13 because the bits specified for word12 (3) do not include those specified for word13 (3 and 4). Word13 is not in a hierarchy above word12 because the values of the bits specified for word13 (1 and 1 for bits 3 and 4, respectively) do not dominate the values of the same bits for word12 (1 and 0, with the 0 for bit 4 implicitly assumed).
Example 8-7 No Hierarchy
name= word12; markings= 3; name= word13; markings= ~3 ~4;
It is always possible to specify all bits involved in hierarchies (leaving no bits implicitly 0). Allowing bits to be implicitly assumed to be 0, as the the first example above, is a convenience that can be used only for hierarchies—or portions of hierarchies—involving normal bits. If an inverse bit appears in a word in a hierarchy, all words above that word in the hierarchy must have the inverse bit explicitly specified.
Appendix B, Annotated Sample Encodings contains the following examples of information label words in hierarchies: CC, SB, bravo1, bravo2, bravo3, bravo4, B, alpha1, alpha2, alpha3, A, all eyes, p1 eyes only, p2 eyes only, WNINTEL, NOFORN, REL CNTRY1, REL CNTRY2, and REL CNTRY3. Appendix B, Annotated Sample Encodings also contains a graphical representation of the hierarchical relationships among these words.