What does the search function in Log window search?

What is searched by the search function? If I copy the log to clipboard and search it in a text editor I find many more instances of most search terms than the seach function does. It looks to me as though search only finds action descriptions, not action output? Interestingly, the copy-to-clipboard code leaves out action descriptions. That's making it somewhat annoying to chase an error that I'm having.

Hmm, faking it a bit (bold is stuff that shows in the log but not the clipboard):

Set File Attributes

File spec : C:\Code\6.5\Projects\~FinalBuilder Scripts\..\*.*
Processed File : C:\Code\6.5\Projects\~FinalBuilder Scripts\..\Cipher Web OGDP\DMECipherOGDP_deploy\DMECipherOGDP_deploy.wdproj
If I search the above for "deploy" in the clipboard I get two hits, but FinalBuilder doesn't find either of them, but if I search for "file" it comes up in both. I'd ideally like to be able to put keywords into the log and filter the log by them, but currently the filter step doesn't work.

I'm not sure whether I would prefer more stuff in the clipboard or more seach options, I think the latter.