The following practices help you create a correct label_encodings file that can be safely extended later.
Caution - For CLASSIFICATIONS and COMPARTMENTS, the security administrator can later change the textual representation. However, the integer and bit values cannot be changed without potentially serious complications.
For example, you could number classifications in increments of 10. The increments allow intermediate classifications to be added later.
Leave gaps in compartment bit numbers for possible later additions.
If your site uses inverse compartments, see Default and Inverse Words. To learn more about inverse compartments, see Compartmented Mode Workstation Labeling: Encodings Format .
As described in Figure 1–2, the total number of classification values that you can use is 254. Do not use classification 0.
A Trusted Extensions system treats a classification value of 10 as more security-sensitive than a classification value of 2. The textual representations are not used to determine security levels.
The same classification value cannot be assigned to different names. Each classification must be higher or lower, or disjoint, from any other classification. Every classification must be distinct.
A table can be used to plan classifications. For a completed example, see Table 6–2.
Decide how data and programs are grouped. Decide whether any data or programs can be intermixed. For example, perhaps purchase order data should not be viewable by programs that manage personnel files. Perhaps purchase order data should be accessible to programs that address shipment tracking problems.
CLASSIFICATIONS and WORDS (for compartments) in the label_encodings file have two forms: a mandatory long name and an optional short name. Short names can be used interchangeably with long names when labels are being specified.
Compartments are not intrinsically hierarchical. However, compartments can be configured to have hierarchical relationships. Before setting up relationships, study the example section in Compartmented Mode Workstation Labeling: Encodings Format .
To make this step easier, use a large board and pieces of paper that represent your classifications and compartments. For an example, see Figure 2–1. With this method, you can visualize the relationships and rearrange the pieces until they all fit together.
Figure 2-1 Sample Planning Board for Label Relationships
You can use a table to plan clearances. For a completed example, see Table 6–5.
When you assign a clearance to a user, the classification component of the clearance must dominate all classifications at which the user can work. The clearance can be equal to the user's highest work classification. The compartment component of the clearance must include all compartments that the user might need.
A table can be used to track compartment bit assignments. For a completed example, see Table 6–4.
Although Trusted Extensions does not support information labels, the INFORMATION LABELS: WORDS: section must be identical to the SENSITIVITY LABELS: WORDS: section to be a valid encodings file.
For suggestions and examples, see Specifying Colors for Labels.
On a system that is configured with Trusted Extensions, use the chk_encodings -a command to generate a detailed report on the label relationships in your label_encodings file.
# chk_encodings -a encodings-file