The Define Line Portion tool
edits the vertices for a portion of a linear route feature identified by tracing and clicking two points along the route. This tool is available in the Modify Features pane.
As you trace along the selected route, the current m-value appears near the pointer in a pop-up. After defining the portion to edit, you can edit m-values in the geometry properties table or right-click and use the m-value commands.
To define a portion of a route, complete the following steps:
- On the Edit tab, choose your snapping preferences, and show the Modify Features pane.
- In the Snapping group, click the Snapping drop-down menu
and enable your snapping preferences. - In the Features group, click Modify
.
- In the Snapping group, click the Snapping drop-down menu
- Expand Route, and click Define Line Portion
.- To exit the tool, press Esc.
- In the tool pane, click Select
, and select the route feature.- To refine the selection, right-click a feature in the tree view, and click Unselect
or Only Select This
.
- To refine the selection, right-click a feature in the tree view, and click Unselect
- Trace and click two points along the selected linear route feature that defines the portion of the line that requires updating. After clicking the second point, the selected feature vertices for the defined portion are editable and their values appear in the geometry properties table.

- To remeasure this portion of the route, edit the m-values in the geometry properties table or right-click a segment, click M Value, and click the corresponding command.
Insert Vertex At M

Inserts a vertex at a specified Measure value in the same direction in which the m-values are increasing.
Apply Factor

Multiplies all m-values by a specified Factor value.
Offset

Sums each m-value with a specified Offset value.
Calculate NaN

Replaces all unknown (NaN) m-values with a value that is interpolated or extrapolated from existing m-values.
Drop Measures
Resets all m-values to unknown (NaN).
Set As Distance

Assigns m-values to all vertices starting with a specified Starting M value and interpolating the remaining values across the geometry length of the feature.
Set From/To

Assigns the specified From and To m-values to the start and end of the feature, respectively.
Set Direction As M

Flips the geometry direction to match the direction in which the m-values are increasing.
- To move, add, or delete vertices or edit segments, right-click a vertex or a segment and click the corresponding command, or use the commands on the toolbar.

Select Vertex
Selects and drags vertices. Click the drop-down arrow to change the selection method.
Add

Adds a vertex with each click.
Delete

Deletes the clicked vertex.
Stretch Proportionately

Preserves the general shape of the selected feature by scaling segments proportionately when you move a vertex. This setting is turned off by default.
- To finish the feature, right-click and click Finish
, or press the F2 key.