Union-All Design Specification. Please help review

[Hsuan Yi Chu]

Hi all,
The Union-All design specification can be found from the following link:

https://docs.google.com/document/d/1OQFQ6IvdeBJkDLKHFBlwP3tle2WuzpBgZf6R_6Vh0mw/edit?usp=sharing

Please help review it and provide some feedback. Thanks.