well I'm not the best modules expert here around.. but I suppose B must go under A if B extends A functionalities.

Infact if you have Transports::Land you can have Transports::Land::Motrobike that extends the first one and Transports::Land::Motrobike::Kawasaki to extends it further.

Normally each :: sign correspond to a directory level; so you'll have Transports/Land and Transports/Land/Motrobike and Transports/Land/Motrobike/Kawasaki directories structure.

See also:

• José's Guide for creating Perl modules
• cpan-tutorials
• What are the files in a CPAN distribution?
• Template to create modules

My homenode contains lot of links about module creation.

HtH

L*