vertical space..under the staff

[Paul Malcolm]

Most of the offsets and padding for objects seem to be for above the staff. 

I would like to display a filled square and triangle for indications of 5/8  

time beat groupings, but I want them underneath the staff.  

For example under the given C note

c4.\DB^\markup{\center-align \larger \triangle ##t}

Is there please some way to control and fix and offset (below) the staff 

for this triangle ? 

Paul