A map theme is a collection of all layer styles, zoom
levels, symbols, and how zooming affects each map configuration.
For example, you can specify a set of visual properties in the Map
Style Property Sheet, such as whether elements are visible or not,
the transparency level, and the color, line thickness, or label for
each layer. You can then associate these properties with a selected
zoom level and when a zoom operation crosses the zoom threshold,
the next style set is applied dynamically. In other words, you can
display a style set per scale range, (see
Setting dynamic styles).
There is no limit to the number of zoom levels that you can define
that trigger a change in the appearance of a map.
For example, in a map of an entire country, the cities
could display at a zoom level that shows the whole country. When zooming
in, you can see only street and building map layers, and when zooming
out only the motorways and cities.
Symbols can also be added to a map and contribute to
the overall theme, but this must be done outside of the Map Builder. Symbols are placed in their own layers and can
be set to visible or invisible.