What is the rule for the punctuation marks for a bicyclo compound?
The current version of Nomenclature of Organic Chemistry – IUPAC Recommendations and Preferred Names 2013 (Blue Book) reads as follows:

P-16.2.2 Full stops
Full stops are used to separate numbers that denote lengths of bridges in polyalicyclic names constructed according to the von Baeyer system (…) and of chain lengths between spiro atoms in von Baeyer spiro names (…).

Examples:
bicyclo[3.2.1]octane
6-oxaspiro[4.5]decane