+ * Answers true if the ref looks like a primary (direct) database reference. <br>
+ * The only way a dbref's mappings can be fully verified is via the local
+ * sequence frame, so rather than use isPrimaryCandidate directly, please use
+ * SequenceI.getPrimaryDbRefs(). <br>
+ * Primary references indicate the local sequence data directly corresponds
+ * with the database record. All other references are secondary. Direct
+ * references indicate that part or all of the local sequence data can be
+ * mapped with another sequence, enabling annotation transfer.
+ * Cross-references indicate the local sequence data can be corresponded to
+ * some other linear coordinate system via a transformation. <br>
+ * This method is also sufficient to distinguish direct DBRefEntry mappings
+ * from other relationships - e.g. coding relationships (imply a 1:3/3:1
+ * mapping), but not transcript relationships, which imply a (possibly
+ * non-contiguous) 1:1 mapping.
+ *
+ * @return true if this reference provides a primary accession for the
+ * associated sequence object