Mapping with Eligibility and Availability

As illustrated at the beginning of this section, Eligibility can be viewed spatially in the Map Viewer. This is accomplished by 'Applying' a Timing Constraint table, which populates the Unit, Zone and Eligibility columns of the Block Table. These columns can then be used to define a new legend for the Block layer in the 'Layer Properties - Symbology' tool (see Adjusting Map Symbology). This would display the Eligibility (Available, Manual or Unavailable) of each Block in the dataset for one particular period. The slider bar on the Map Viewer can be used to view changes in Eligibility over time.

It is important to distinguish between Eligibility and Availability in the Block Table. Fine tune changes can be made in the Block table by toggling the Availability check boxes for each individual Block after the Timing Constraint table was applied. Changing the Availability column does not change the Eligibility column, therefore the Eligibility map may be somewhat misleading or even inaccurate.

Another misleading characteristic of the Eligibility theme is the assignment of Green (available) to unmanaged Blocks. This is somewhat misleading, as unmanaged Blocks are never available to the scheduler by definition. Eligibility is assigned based on the Unit attribute, and does not take the management status into consideration.

For a detailed view of the actual Availability of all Blocks in the dataset, the 'Availability' column should be used as the unique value in the Legend. This will provide a True/False classification for each block, always considering the 'managed' or 'unmanaged' status of the Block. It is this column that ultimately constrains the scheduler when the model is run, and therefore adheres to all treatment rules.

Figure 65. Availability vs. Eligibility

It is best to think of Eligibility strictly in terms of the Unit being considered (ie. whether or not the Block is eligible in terms of Marten areas 0-6), and Availability as an overall classification that takes all constraints into consideration. The Block Availability Report (csv) is derived from this column in the Block Table and is saved with each scenario to establish the exact condition of each block.