Why this distinction?

[terrypin]

Terry, East Grinstead, UK

[ovg]

Did you set "Match Whole Word" in search Menu?

[terrypin]

Thanks. Not sure as I've been experimenting since, and files have also changed. But I'm sure you've identified the cause. I'm confused though. What is a 'whole word'? Does punctuation like a minus sign or full stop signal the end of a word? That appears the only way that IrrigUnit-1.WAV differs from those other results?

[vanisk]

Does punctuation like a minus sign or full stop signal the end of a word?

Yes, AFAIK Space, Tab, Carriage Return and other punctuation marks (which includes hyphen/minus sign) (i don't have the complete list, I'm expecting that someone will post here) are considered as end of word markers.

[ovg]

AFAIK only letters,digits and underscores are allowed as word symbols, but I may be wrong

[void]

Everything considers the following characters as part of a word:
a-z
A-Z
0-9
any non-ASCII character.

Anything else is consider a word break.