Can upper case filenames be found in a lower case search?

[Mahombi]

Can anyone tell me where we stand nowadays with using upper case letters in filenames?

I have read from several sources, that one "should not expect an image with a filename consisting of upper case letters, to be found in a search done using lower case" and vice versa. I cannot attest to the age (or accuracy) of this information, but I'm assuming that it is now out of date, given that in The DAM Book, Peter uses both upper and lower case (as in his name) in his filenames. 

Thanks in advance.

Terry