true iff begin/abort/commit are implemented and make sense.
begin
void begin()
If transactions are supported, begin a new transaction. If tranactions are
not supported, or they are but this tranaction is nested and nested transactions
are not supported, throw an UnsupportedOperationException.
abort
void abort()
If transactions are supported and there is a tranaction in progress, abort
it. If transactions are not supported, or there is no transaction in progress,
throw an UnsupportedOperationException.
commit
void commit()
If transactions are supported and there is a tranaction in progress, commit
it. If transactions are not supported, , or there is no transaction in progress,
throw an UnsupportedOperationException.