Field manual · 04/17

Coordinates & Position

Reading and writing position is what this app is for. More than thirty coordinate formats, forty-seven geodetic datums, any projected system by EPSG code, and a search field that takes whatever you paste into it.

the position screen

The Position tab is your own location, in full. Cards show the coordinate in your chosen format, accuracy, altitude, speed, heading, the date and time, and the weather where you stand.

Reorder the cards

Hold a card and drag it. Put the two readouts you actually use at the top and the rest below.

Local or Zulu

Tap the TIME card to flip between local time and Zulu. The app-wide default is in Settings → Formats & Units; this is the quick look.

The speedometer

Tap the SPEED card for a full-screen speedometer — an expand glyph in its corner marks it as tappable. Two styles: an analog 270° dial with an auto-ranging scale, or a digital bar. A trip row shows MAX, time-weighted AVG and RESET, counted since you opened the screen.

The speedometer notices when you are driving — a sustained 25 km/h for three seconds — and widens the dial so a steady cruise sits mid-scale like a car's instrument rather than pinned at the top.

The readout at the top of the map shows the crosshair position, not yours. Tap it to cycle through coordinate formats without opening Settings.

coordinate formats

Settings → Formats & Units → Coordinate Format opens the picker, grouped exactly as below. Every row previews your live fix, or a sample position when there is no fix, and can be starred into Favorites at the top of the list.

Format	Shown as	Note
Grid systems
MGRS	`18S UJ 23394 06753`	Military Grid Reference System
USNG	`18SUJ2339406753`	Same grid as MGRS, written unspaced
UTM	`18N 323394 4306753`	Zone, easting, northing
National grids
BNG	`TG 51409 13177`	OSGB36 · Great Britain
BNG E/N	`651409 313177`	Same grid as BNG, all-numeric
Irish Grid	`O 15904 34671`	TM75 · Ireland
ITM		ETRS89 · Ireland
SWEREF 99 TM		Sweden
ETRS-TM35FIN		Finland
NZTM2000		New Zealand
CK-42 (GK)	`7412345 6177345`	Pulkovo 1942 · Russia & CIS · zoned
CK-42 (GK) X/Y	`6177345 7412345`	Same grid as CK-42, X (north) first
India NSF LCC	`4123456 3456789`	WGS 84 · India · EPSG:7755
Projected
EPSG PRO		Any projected coordinate system by EPSG code
Global codes
Plus Code	`8FVC9G8F+6XQ`	Open Location Code · worldwide, ~3 m
Maidenhead	`JN47gj12ab`	Amateur radio QTH locator · worldwide
India Sheet (OSM)	`F44H13`	Survey of India Open Series 1:50 000 sheet
India Sheet (IAC)	`53H/13`	Survey of India older-series 1:50 000 sheet
Degrees
DDM	`DDD° MM.mmm'`	Degrees and decimal minutes — marine & aviation
DMS	`DDD° MM' SS"`	Also with one and two decimal seconds
DD	`DDD.dddddd°`	Four, five or six decimal places

The coordinate format picker showing MGRS, USNG and UTM with a live fix preview — Coordinate formats

Every degrees format has a ± variant that writes a signed number instead of a N/S/E/W suffix — which is what most software wants when you paste a coordinate into it.

USNG is MGRS. Same zone, same band, same 100 km square, same digits — only the spacing differs. It exists because US search-and-rescue, emergency management, wildland fire and National Park Service forms expect the unspaced notation. If a form asks for USNG, write 18SUJ2339406753, not 18S UJ 23394 06753.

CK-42 comes in two axis orders because Soviet map series and GLONASS receivers report X (north) before Y (east), while EPSG and the rest of this app put easting first. Pick the one that matches the sheet or the receiver in front of you.

India has three of its own. India NSF LCC is the national Lambert grid (EPSG:7755); India Sheet (OSM) and India Sheet (IAC) report the Survey of India 1:50 000 sheet number instead of a coordinate — the Open Series notation (F44H13) and the older IAC notation (53H/13) respectively, so you can name the map sheet you are standing on.

Grid-square formats wrap to two lines in the big readouts, but the clipboard always gets the canonical single-line string — so a copied coordinate pastes correctly wherever it lands.

Outside a national grid's area the readout says Outside <grid> coverage rather than printing a number that means nothing there.

secondary readout, favourites and utm options

Secondary Format

Settings → Formats & Units → Secondary Format puts a second line under the primary one on the Position screen, the crosshair panel and the pin preview. Set it to Off or to any format. MGRS on top and decimal degrees underneath covers both the radio and the spreadsheet.

Favorites

Star the formats you switch between and they pin to the top of the picker, so changing format is two taps rather than a scroll through the whole list.

UTM options

When UTM is your primary or secondary format, two more rows appear: UTM Decimals (0, 1 or 2) and UTM Unit (Meters or Feet).

UTM in feet is display only. The readout converts, but every parser in the app still reads metres — so a coordinate you type or paste is interpreted in metres regardless of this setting.

any epsg system PRO

Choose Projected (EPSG) in the format picker to open Coordinate Systems: 57 curated national grids grouped by country, a search field, and a free-text Any EPSG code box with a Use button.

The curated list covers Australia, Austria, Belgium, Brazil, Bulgaria, Canada, Croatia, Czechia, Estonia, France, Germany, Great Britain, Greece, Hong Kong, Hungary, India, Israel, Italy, Japan, Latvia, Lithuania, Luxembourg, Mexico, Morocco, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, South Africa, South Korea, Spain, Sweden, Switzerland, Taiwan and the United States — for example RGF93 / Lambert-93 (2154), CH1903+ / LV95 (2056), Amersfoort / RD New (28992), Belgian Lambert 2008 (3812), the Austrian GK zones (31254–31256) and OSGB36 / British National Grid (27700).

Each system carries its area of use, so the picker previews your position in it and warns when you are outside where it applies.

If the code you need is not in the list, type it. Anything the projection library can resolve works; anything it cannot reports a readable error rather than failing quietly.

The Apple Watch has no projection library, so a coordinate format set to EPSG falls back to UTM on the wrist. Every other format reads the same there.

geodetic datums

Settings → Formats & Units → Geodetic Datum lists 47 datums, searchable by name, region or EPSG code. The default is WGS84, which is what GPS itself reports.

The list covers ETRS89, ED50 with its regional variants, NAD27 and NAD83, OSGB36, TM75 and IRENET95, RGF93, DHDN, Amersfoort, CH1903+, SWEREF99, Pulkovo 1942, Tokyo and JGD2011, Korean 2000, CGCS2000, Hong Kong 1980, Indian 1975, Kertau, Timbalai, Israel 1993, Qatar, Nahrwan, Adindan, Arc 1950 and 1960, Minna, Hartebeesthoek94, SAD69, SIRGAS 2000, AGD66, GDA94, GDA2020, NZGD49 and NZGD2000, among others.

A datum is not a formality. The same grid reference on WGS84 and on ED50 can be a few hundred metres apart. Match the datum printed in your map sheet's margin, or your plot will be consistently wrong in a consistent direction.

National grids and global codes carry their own datum and ignore this setting — British National Grid is always OSGB36, the Irish Grid always TM75, a Plus Code always WGS84. The datum picker governs the lat/lon, UTM and MGRS families.

precision datum grids PRO

A datum conversion done with a seven-parameter transformation is good to about a metre. A grid shift file does it properly, by interpolating the actual distortion of the national survey. The datum picker's Precision Grids section downloads them.

Grid	Applies to	Download	Accuracy
OSTN15	OSGB36 · Great Britain	~5 MB	±0.10 m
OSi / OSNI	TM75 · Ireland	~1 MB	±0.15 m
NADCON	NAD27 · US (CONUS)	~6 MB	±0.15 m
NTv2	NAD27 · Canada	~13 MB	±0.15 m

Rows read Download <size> before installing and Installed · ±x.xx m afterwards. Without a grid installed the app falls back to a Helmert transformation, which is metre-class in these regions.

You can supply your own: Import NTv2 Grid (.gsb) loads a grid file for the selected datum. A file the app does not recognise reports The file is not a readable NTv2 grid. An imported grid of unknown provenance is only claimed as metre-class.

north reference and angle format

There are three norths and they disagree. Settings → Formats & Units → North Reference picks which one every bearing in the app uses:

True North: The geographic pole. Tagged T.
Magnetic North: What a compass needle points at. Tagged M.
Grid North: The vertical grid lines on your map sheet. Tagged G.

Under the picker sit live Declination and Grid Convergence readouts for your current position, written the way a map sheet's declination diagram writes them — 3.4° E. Declination comes from the device compass; convergence is computed from your grid zone.

Angle Format

Degrees (360), US/NATO Mils (6400), Soviet Mils (6000), Gradians (400) or Quadrant Bearing — the surveyor's N 45° E notation, which never exceeds 90°.

Bubble level

The compass carries a bubble level under the bearing. It turns green inside ±3° — the tolerance a hand-held bearing actually needs. It is hidden on devices without motion sensing.

Quadrant bearing is a notation rather than a unit, so it appears in bearing readouts but not in the Unit Converter's angle list.

search and the any-format field

The Search tab has four tabs — Coordinate, Grid, Search Pins and Address Search — and above them a single Any Format field.

Paste anything

Paste or type a position in almost any notation and the app identifies it, tells you which format it recognised, and fans the value out into the other tabs so GO just works. Unrecognisable text reports Not recognized rather than guessing.

The field accepts MGRS and USNG; UTM with a band letter or a hemisphere letter, including zero-padded seven-digit eastings such as 33T 0293000 5010000; Plus Codes, full or short; Maidenhead locators from two to ten characters; decimal degrees, degrees-decimal-minutes and degrees-minutes-seconds in every common spelling; lettered or numeric national grid references; and EPSG:<code> x y triples.

Project a point

Project From Me and Project From Center compute a new position from a bearing and a distance — the digital version of a resection, and how you plot a point given as "1 200 m on a bearing of 073".

The Back Bearing switch projects along the reverse azimuth instead, for when the bearing you were given runs the other way.

Short Plus Codes are resolved against the map centre or your position, so 9G8F+6XQ works without the region prefix when you are already nearby.

Search Pins searches your saved items by name; Address Search looks up addresses and place names and is a Pro feature. Coordinate and grid search are free.

The Search screen with a grid reference entered and the result ready to jump to — Coordinate search

the coordinate converter

Tools → Coordinate Converter converts between MGRS, UTM and Lat/Lon on a dedicated screen, with the same input mask, parser and validation the Search screen's GRID tab uses. Free.

For a conversion into a national grid or a projected EPSG system, set that system as your Secondary Format instead and read both at once on the Position screen.

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