IndexedTraceAccess is used to represent accessing an element in the execution trace during
constraint evaluation. The trace_segment specifies
how many trace commitments have preceded the specified segment. col_idx specifies the index
of the column within that trace segment, and row_offset specifies the offset from the current
row. For example, an element in the “next” row of the “main” trace would be specified by
a trace_segment of 0 and a row_offset of 1.
NamedTraceAccess is used to indicate a column in the trace by specifying its index within a
set of trace columns with the given identifier. If the identifier refers to a single column
then the index is always zero.