The relationships between the entities which are used to store the two dual DCELs can be best understood by the following overview of access macros which are used to select the entries of the data entities.
Table 6.2: Macros for accessing the DDCEL data structures
Referring to the example graphs in Figure 6.6, the following relationships between entities can be observed:
Tagged blocks are used as data strutures. The tag field of an entities contains the following information.