Letter Sheet offsets are a series of offset points defined by the points marked on a Letter Sheet target sheet. The 10 offset points can be used to define an edge or a line feature without having to place targets right on that edge or line.
The offsets are based on the 6 targets on the Letter Sheet based on a ratio of the distance between pairs of targets. The blue points in the image below are defined automatically based on target id ranges.
The offset points are defined like RAD offsets where the offset distance is based on a ratio of the distance between two targets.
For example, the offset to the right of Target Point #2 in this example, is 1.59x the distance between Point #1 and Point #2, from Point #1, along the vector defined the two points in the pair. The offset point above Target Point #2 is 1.543x the distance between Point #4 and Point #2, from Point #4 along the vector defined by the two points.
These are the default values for these types of offsets, but these ratios can be adjusted. See Coded Target Presets and Coded Target Presets Dialog. Letter Sheet Offsets are applied to a project during an Automated Target Project (if a configuration is set to be applied), but they can also be applied to a project using the Coded Target Offsets Library.