There are four generic types of highway shield: county, interstate, state and national. Each type has three layers, each of them optimized for a specific zoom level display.
The layers contain fixed-point shields. When one of the layers is added to a map window, the shields display on top of the appropriate Highways layers. The text specifying each route number is drawn from an autolabel on the associated Shields layer.
Each type of shield is contained in separate tables, organized by county (in county-tiled
packs) or by state (in state-tiled maps).
Note: To support the independent use of highway
shields, a lookup table— StreetProUSHighwayShieldRefer.tab—has been included
in StreetPro Display United States and above. It lists, for each Shield code, a
description of the highway type and the associated MapInfo Pro symbol
definition.