Why single periods in regex in spamassassin rules?

[Steve Dondley]

I'm looking at KAM.cf. There is this rule:

body    __KAM_WEB2  /INDIA based 
IT|indian.based.website|certified.it.company/i

I'm wondering if there is a good reason why a singe period is used 
instead of something like \s+ which would catch multiple spaces whereas 
a singe period doesn't.