The Aprx uses following configuration schema, which took its model very much from how Apache HTTPD configuration is done. To denote elements without < .. > around them as Apache does, we use "uri:apache:config" style bits, like: <ht:element> Because Apache's configuration predates XML and schemas, there has never been proper XML-like schema for it or anything alike it, nor is this intended to be validatable by XML tools. The overall syntax is line oriented, along with \ -characters at the end of line as continuation markers to append next line in place of that character plus the end-of-line character(s). Anywhere (except when previous line ends with \ -character) if the first non-white-space character is '#' the whole line is comment, and is discarded. Lines containing only white-space characters are also comments and are discarded. Presence of non-quoted '#' at the tails of parameter lines should also behave as comment, but it is not universal. Presence of extra parameter values is not always flagged as an error. The overall Aprx config contains parameter groups, and one top-level parameter label. The "mycall" parameter label must be before anything else. The <interface> and <aprsis> groups follow, and the rest that use those interfaces then follow. The <logging> group can be anywhere. Each group can occur multiple times. The Aprx configuration has flexible time interval definitions. A string of decimal numbers followed by multiplier character: 12 d 2 h 20 m 24 s 50 h 70 m 200 s 200 s 3 h Whatever notation is easiest to understand for the use. The multipliers are single characters and case insensitive. Embedding white-space is permitted for readability. ("d" = days, "h" = hours, "m" = minutes, "s" = seconds) This is ASCII representation of AX.25 callsign. Up to 6 upper-case letters (A-Z) and digits (0-9), then possibly a minus ('-') and decimal number 0 to 15. By convention a "-0" is never used. This is more relaxed form of AX.25 callsign: Regular expression: [a-zA-Z0-9]{1,6}($|-[a-zA-Z0-9]{1,2}) Or verbally: Up to 6 alphanumeric characters + optional tail of a minus ('-') followed by one or two alphanumeric characters. Also lowercase letters are allowed in alphanumerics. The APRSIS group defines communication parameters to APRS-IS network. The Login parameter for APRS-IS network. The Aprx will calculate correct authentication parameter for that login value. Defines server to which the Aprx connects for the APRS-IS service. serverhost [portnum] Chosen servers should be regional round-robin ones, see http://www.aprs2.net/ noam.aprs2.net soam.aprs2.net euro.aprs2.net asia.aprs2.net aunz.aprs2.net or the global pool: rotate.aprs2.net You SHOULD NOT connect to any specific one, as none of the servers are behind a load-balancing fail-over mechanisms. One white-space terminated parameter that is fed to APRS-IS server immediately after a login. If multiple filters are needed, they are defined with successive 'filter' parameter entries. The Logging group defines how the Aprx does logs. Without it, or any parameters inside it, no logging happens.