auto-snap-switch ("asn")

See this command in the command table.

To access this command:

Home ribbon >> Snap >> Auto Snap
Digitize ribbon >> Snap >> Snap Mode >> Auto Snap.
Using the command line, enter "auto-snap-switch"
Use the quick key combination "asn".
On the Find Command screen, highlight auto-snap-switch and click Run.

Command Overview

A digitizing switch that, if enabled, will snap to nearby data regardless of the current snap settings.

If no data is nearby, non-snapping/freeform digitizing is performed.

This mode can be used in conjunction with other digitizing modes such as Auto Node, for example.

Note: There's no need to set up snapping modes when digitizing data (say, a polygon feature) onto a wireframe map. The closest wireframe vertex will always be the point at which a line vertex is positioned.