How a Two-Letter Code Turns Dots Into a Drawing
A total station on its own doesn't know if the point it just measured is a manhole cover, a curb, or a tree. All it captured is a coordinate: easting, northing, height. Without a code attached, that point is just a dot floating in space, indistinguishable from a thousand other dots on the same job.
Field codes fix this. A short alpha or numeric tag entered alongside every shot tells the office software exactly what it measured, and increasingly, how to connect it to neighbouring points automatically. This is the difference between a raw scatter of coordinates and a finished plan the moment data comes off the instrument.
Crack the Code
Match each field code prefix below to what it actually tells the plotting software to do. These prefixes come straight from real field-to-finish survey software.
💻 Field Code Terminal
The Prefix Toolkit
Joins points with the same descriptor into a connected line, like stringing curb shots into one continuous curb.
Same joining behaviour as Z, but introduces rounding, useful for curved features like a curved kerb line.
Joins the last identical descriptor with a line drawn at a right angle, handy for fence corners and similar features.
Creates a dot in the drawing, which can later be swapped for a real symbol: a tree, manhole, or hydrant icon.
Why Some Crews Code Everything, and Some Code Almost Nothing
There's a real productivity trade-off here. Crews that record a descriptive code for every single point typically capture 200 to 300 points in a working day. Crews that keep coding to the bare minimum, adding descriptions later at a computer instead, can push through 300 to 700 points a day. Neither approach is universally right, it depends on whether speed in the field or immediate map readability matters more for that specific job.
This coding discipline is exactly what feeds a clean GIS Solutions dataset later, since the same point codes that draw a curb line in the field also become the attribute data a GIS uses for asset management down the line. It ties directly into broader Feature Geo Tagging practice used across almost every survey type.
| Code | Meaning |
|---|---|
| OCC / 10 | Occupied station (where the instrument stands) |
| BS / 20 | Back sight |
| FS / 30 | Fore sight |
| IS / 40 | Intermediate sight (general topo point) |
"A coordinate tells you where. A field code tells you what. A finished map needs both."
The next time a finished topographic drawing appears on screen just minutes after a crew returns from site, with curbs, fences, and manholes already correctly drawn, that speed isn't magic. It's the direct payoff of a short alphanumeric code entered at the moment of measurement, doing quietly in the field what used to take hours of manual drafting back at the office.
Note: the WhatsApp number/chat below is for project leads only, not for guidance, learning queries, or general doubts. If you have an actual survey project to discuss, reach out and our team will respond.
💬 Send a Project Enquiry