Background

GPX files are an XML based way of storing GPS date - waypoints, routes, and tracks. Since NGS»GPX was designed as a way to import more information from the official datasheet into GSAK and contain the most amount of information, the GPX (1.0) schema for XML was used, along with the GSAK and Groundspeak extensions. The base schema for the GPX file contains basic file information (author, date, etc) and then can have one or more waypoints, tracks, or routes. Now, for benchmark stations, we are only interested in the waypoints.

The Waypoint type in the base GPX definition allows for several useful bits of information:

• Elevation
• Time (usually used for when the waypoint was created, but could also be the last visited, etc.)
• Magnetic Variation (at this point, how far Magnetic North is from True North)
• Name
• Comment (Any added comments by the user or visitor of the point)
• Source (Who or what created the point)
• Symbol
• Type (What category the waypoint is)
• GPS Fix (What kind of fix the GPS device had when creating this point)
• Satellites (How many satellites were in use when the point was created)

Now, obviously for benchmarking (and geocaching), many of these aren't used. For example, when we download a cache, we expect the coordinates to be exact, so we wouldn't use the GPS Fix. And very little - if any - caches care about the elevation, and if they do, it's in the text of the cache, not data specific to the cache.

There's also information that is needed that does not have a set place for it in the Waypoint schema. Groundspeak added an extension (v1.0) to the waypoint schema to contain specific cache data. You will begin to see here, that there is some inconsistency and needless overlapping of date here, as well:

• Placed By (Who placed the cache)
• Owner (Who owns the cache at the moment. According to schema, there can be more than one owner.)
• Type (The cache type)
• Container (The container type of the cache)
• Attributes (Specific attributes for the cache)
• Difficulty / Terrain
• Country / State
• Short and Long Description
• Encoded Hints
• Logs (can contain more than one log, so a GPX file, in theory, can have the log of everyone who visited it exported)
• Travelbugs (Any travelbugs reportedly at the cache)
• Available (Whether it's available or not)
• Archived (Whether it's archived or not)

You'll note here some available options that aren't taken advantage of - either by GSAK or GC.com. Namely, the Attributes. According to what little documentation I could fine, attributes would have a unique ID, and would help describe a cache. For example, attribute #10 could be "Downtown City", and every cache that was downtown in a city would have this attribute. Also note that the "type" field is duplicated from the main waypoint schema.

Usage

Since benchmarks were never intended to be part of the GPX system with Groundspeak (and still aren't), some fields available to GSAK had to be used for other benchmarking information. GPX files created by NGS»GPX are still readable and understandable by other programs that read GPX files (such as Google Earth).

Here's a list of the elements in a GPX file whose usage differs from a normal GPX file:

• <name> / <wpt:gsak:smartname> - The PID of the station.
• <desc> - Files created by NGS»GPX have the file description as "Benchmark GPX created by NGS-GPX (HasChildren)". The (HasChildren) is needed for GSAK to load Children waypoints, and will only exist if the option to process reference marks is enabled.
• <wpt:desc> / <wpt:groundspeak:name> - The designation of the station.
• <wpt:time> - The date of the file that the benchmarks were taken from. If the "Try to use DB Date" setting is enabled, it will either be the LastModified time of the input file, or the database pull line that looks like:
  

  1        National Geodetic Survey,   Retrieval Date = JANUARY 16, 2008 

  
  Often, in files that have more than one of the line referenced above, the last one will take precedence over any others. (Usually, however, they're all the same date anyways.
• <wpt:sym> / <wpt:type> - While these would be useful for benchmarks and determining what the type of the station is, for GSAK to properly recognize one as found - without interrogating logs - they have to be "Geocache"/"Geocache Found" for <wpt:sym>, and "Geocache|Benchmark"/"Geocache|Benchmark|Found" for <wpt:type>.
• <wpt:groundspeak:placed_by> / <wpt:groundspeak:owner> - The Owner and Placed By is the first agency listed in the History Record section of the datasheet. The Owner ID is a negative number, the first four letters of the agency code converted to their ASCII equivalent.
• <wpt:groundspeak:type> - Normally, the type is simply "Benchmark". However, by enabling the setting "Use Type for Station Type", the type may be "Mystery", "Locationless", or "benchmark", depending on the type of the station. This will change the appearance of the icon in GSAK.
• <groundspeak:container> - This is the horizontal accuracy of the coordinates. "Scaled", "Adjusted", "HH_GPS".
• <wpt:groundspeak:difficulty> / <wpt:groundspeak:terrain> - Will always be "1".
• <wpt:groundspeak:country> - Will be "USA", unless the setting "County in Country" is enabled, the county of the mark will be inserted into this field.
• <wpt:groundspeak:logs> - Logs are parsed form the datasheet recoveries, if "Translate Recoveries into Logs" is enabled. The info from the recovery record or the year from the description is used as the date for the log, the status is taken from the recovery record, the finder is taken from the agency, and the text of the log is taken from the recovery description. If a history record has an unknown date or finder, then the next known one is used. If a history recover has no text, a default message is used for the log text. Log statuses that are used are:
  • "SEE DESCRIPTION" (or Unknown) - Log type is "Note"
  • "MOUNMENTED" or "FIRST OBSERVED" - Log type is "Enable Listing"
  • "GOOD" - Log type is "Found it"
  • "POOR" - Log type is "Needs Maintenance"
  • "DESTROYED" - Log type is "Archive"
  • "MARK NOT FOUND" - Log type is "Didn't Find It"
• <wpt:groundspeak:archived> - There are two ways a station may be deemed destroyed - either your Found File has an entry for a destroyed mark, or a log is found with a "DESTROYED" status and you have the setting "Mark Stations as Destroyed" enabled. When either of these are true, the Archived attribute is set to TRUE.
• <wpt:groundspeak:attributes> - In the hope that someday attributes will be used, certain attributes are used by NGS»GPX and put into the GPX log. Currently, GSAK completely ignores these, so they don't have any effect into loading GPX files. However, the attributes used by benchmarks are:
  • ID: -12001; "Mark is a Tidal Bench Mark."
  • ID: -12002; "This is a Cooperative Base Network Control Station."
  • ID: -12003; "This is a GPS Continuously Operating Reference Station. (ID: <CORS ID>)"
  • ID: -12004; "This is a Height Modernization Survey Station."
  • ID: -12005; "This is a Primary Airport Control Station."
  • ID: -12006; "This is a Secondary Airport Control Station."
  • ID: -12007; "This is a Federal Base Network Control Station."
• <wpt:gsak:firsttofind> - Usually False. If the option "Mark Station FTF" is enabled, then if the program finds a "GOOD" or "POOR" log you entered, and the previous log was a "MARK NOT FOUND", then it will set this to "True". Essentially, the "First To Find" field, for benchmarks, would be a "Found a previously not found" recovery mark.
• <wpt:gsak:user2> - Normally empty. However, if the option "Put Altitude in User2" is enabled, then this field will have the altitude of the mark is put into that field in the text format of "00000.000". (If the altitude is unknown, then "00000.00" is put into that field.)

Child waypoints (reference marks) are follow pretty much the same format. However, the <sym> and <type> are different, to represent child marks, and the GSAK extension flags are set.

GPX 1.1

You may be wondering why GPX 1.1 isn't being used. (It does have a lot more features that would be beneficial to Benchmarking and Geocaching, after all!) Well, namely, GSAK doesn't support it. Also, while it's been released back in 2003, and Groundspeak even updated their extensions to 1.1, even geocaching.com doesn't use 1.1, so there's no need to worry about 1.1 at the moment.