DBCC SHOWCONTIG Questions

On most of the results from a series of DBCC SHOWCONTIG
commands, we see an entry for "Logical Scan
Fragmentation", but on others we don't see that entry.
From comparing the tables I can see that a table with only
a clustered index or table with some indexes but none of
which are specified as primary key or clustered are the
ones without the logical scan frag information. Can
someone explain to me why tables with these characterists
don't also generate logical scan fragmentation
information? BOL did not help me figure that one out.
Thanks for any info.that value really only makes sense for tables with a clustered index.
Tables without a clustered index are known as "Heaps". For Heaps, I focus on
the "Scan Density" Value and make sure that it stays above 80%
Cheers,
Greg Jackson
PDX, Oregon