Technically, this is defined as anyone who died in military service between 4th August 1914 and the 31st August 1921 (WW1) and 3rd September 1939 to 31st December 1947 (WW2).
I have been slightly less strict, but then, I don't have to be! In one case I found two brothers - one died within those dates and his name was not listed on his town's war memorial and, yet his brother who died outside those dates, was included. I have also found another two brothers - both were killed in action, but the C.W.G.C. only has a record of one of them.
It is certainly not an exact science and not everything makes sense. I have found men who had been born and raised in a town, but had moved away a year or two before the war, were not included on the memorial. Similarly, men who had just arrived in the town a month or two before going to war have been included. Sometimes names have been left off, I believe, because they died of natural cases and perhaps the families did not think their son of husband qualified to be listed. There is often very little consistency in what I have sometimes found.
I have taken the view that it is not up to me to decide who should be included in these databases and who should not - if I have found any connection with Trafford, however tenuous - then they're "IN".