Both this and the above can be zero. */
unsigned ignore : 1; /* 1 prohibits further processing of giv */
unsigned always_computable : 1;/* 1 if this set occurs each iteration */
+ unsigned maybe_multiple : 1; /* Only used for a biv and 1 if this biv
+ update may be done multiple times per
+ iteration. */
unsigned cant_derive : 1; /* For giv's, 1 if this giv cannot derive
another giv. This occurs in many cases
where a giv's lifetime spans an update to