[daip] flagver

[Eric Greisen]

emily writes:
 > hi eric,  i have one quick question about the behavior of FLAGVER.  if i 
 > have a FG 1 table and i run TVFLG with FLAGVER=2 shouldn't it make a 
 > new table and call it FG 2 and put the new flagging commands there?

Actually the rules of TVFLG on this are complicated and do not now
make much sense to me.  If you tell it FLAGVER=2, it tries to flag
the input data with a non-existent FG table which it handles but then
will not write to a new table.  Most modern flagging tasks copy the
existing FG table, if it is applied to the data, and then always write
a new one (perhaps unless you force it not to).  Note that there are
no tasks to append two flag tables together so one should be careful
writing brand new empty FG tables.

Maybe I should revisit the behavior of TVFLG and SPFLG and even
consider a table append task.  There are already sort and merge tasks.

Eric Greisen