The only parameter required by javAPRS is one of the three map file parameters (without a map, there isn't much point to javAPRS!). All map files must be placed in a folder called "maps" within the "javAPRS" directory containing the class files. javAPRS can display two types of maps. The first is the familiar (to APRS users) dos map format. These maps can be either Normal, Compressed, or Line Format.

<PARAM name="dosMap" value="usa.mp">

Dos maps should have the suffix of ".mp". (".map" is not used, as some HTML servers use this extension for image map files, and these servers will not send files with the suffix ".map" correctly.)

There are several parameters that affect the way dos maps are displayed.

<PARAM name = "showLabels" value = "false"> (default true)

This determines if the labels included in the map file are to be displayed or not. The labels include data that specify at what scales they should be displayed.

<PARAM name = "showAllLabels" value = "true"> (default false)

This causes all map labels to be displayed regardless of the scale selected.

<PARAM name = "autoScale" value = "false"> (default true)
<PARAM name = "offsetX" value = "150"> (default 0)
<PARAM name = "offsetY" value = "200"> (default 0)
<PARAM name = "scale" value = "0.24"> (default 1.0)

The map can either be automatically scaled to be as large as possible but still fit within the boundaries of the applet, or the zoom and scale can be manually specified. autoScale is set to false automatically if a scale parameter is specified.

The values of these parameters must be determined largely by trial and error to get the display you want. In order to make the process easier, the program will print out the value of these parameters to the java console every time a scroll and zoom is done. To use this feature, zoom and scroll the map as desired, then look in the console for the values. Note that these values only specify the initial display; once javAPRS is running the user is able to change the zoom and scroll to suit themselves.

<PARAM name = "backgroundColor" value = "black"> (default gray)

Normally, javAPRS displays dos maps with a light gray background, and callsigns are shown in black. javAPRS can also display maps on a black or white background. There are two separate icon files which are optimized for light and dark backgrounds.