SPARQL - UNION - disjunction issue

The results of UNION as described could still be accomplished through 
other uses of the SPARQL language. Therefore omitting the UNION keyword 
would not greatly change the task of implementing SPARQL.
At the same time, users would come to understand that the use of UNION 
is expensive just as they do when using the same keyword in SQL.
So to avoid implementing such as a useful keyword seems unnecessary.

M. Nichols
Toronto, Canada