[dba-Tech] Quick Word Question

I have a numbered list, and want to add sub-numbers. That is...

1. Item 1
    a) sub-item 1
    b) sub-item 2
2. Item 2

I know I've done this, but not in a while, and can't recall how. Moving to
the end of Item 1 and pressing Enter, then Tab doesn't work. Suggestions?
-- 
Arthur