RewriteRule ([A-Z][a-z]+)([A-Z][a-z]+)?([A-Z][a-z]+)?([A-Z][a-z]+)?([A-Z][a-z]+) 
String: TodayIsMonDayYes
Output:
$0:	TodayIsMonDayYes
$1:	Today
$2:	Is
$3:	Mon
$4:	Day
$5:	Yes

Add Spaces Before Capitals

$regexp(title,(<=\l)(?=\u), )

It looks back one character for a lower case letter, “(?<=\l)”
and then looks forward a character for an upper case letter, “(?=\u)”
putting a space in if both are true. “, )”