Before I am accused of spreading false info, the issue of how long a company (like DLS) must wait before launching a second bid in unresolved. The six month rule is a UK thing it seems, and has been bandied about on this forum once or twice (and repeated by me)
A reference:
http://www.claytonutz.com/publications/news/201106/28/truth_in_takeovers_walking_a_wobbly_line.page