<#block=blocks> taken from various places on a <#sheet=sheet> which show <#guideline=guide lines>, <#arrow-gen=arrows> or other <#marginmark=marginal markings>.

<#perf=perforations> on one side of a <#stamp> that begin as perf 11 and end as perf 10.  These transitional perforations were produced during the early 1920s on some <#flatplate=flat plate> stamps.  The cause was the use of a gauge 11 perforating wheel on which a small section of pins was replaced by a section of gauge 10 pins.

nickname for <#scott=Scott> 467, 485, and 505.  The <#tranroll=transfer roll> for a 5¢ <#stamp=stamp>, normally printed in blue, was mistakenly used on a <#plate> of 2¢ stamps printed in carmine, thus creating a color <#error> for the 5¢ stamp.

island under U.S. administration from 1899 to 1902, and for which <#overprint=overprinted> U.S. <#stamp=stamps> were issued.

one of several types of <#grill=grills> used in the 19th century, about 12 x 14mm in size.  Example: <#scott=Scott> 84.