The RDD marking has double circles with the outer circle always made of multiple lines. It appeared in Tegus in 1891 and remained there throughout its 13 years never to be seen outside the city.
In 1897 the font was changed to sans serif and the inner circle was edited to a single line.
Early usage of the edits to RDD, March 1897. BH73 cancel along with A.R. for return receipt.
Used only in La Ceiba for six years starting in 1927 and ending in 1932. This marking has an outer circle of a single line and an inner circle of multiple lines.
Used only in Puerto Cortés for a year in 1936. Here both inner and outer circles have a single line.
BH50 cancel and RDS registration marking.