Available with 3D Analyst license.
Use the Set TIN Tags 
interactive tool to change node or triangle tags. When the Set TIN Tags tool is selected, the Set TIN Tags dialog window appears, which allows you to specify whether you intend to modify node or triangle tags, how these elements will be selected, and the tag value to assign to them.
- Click the TIN Editing drop-down menu and choose Start Editing TIN.
- Click the Set TIN Tags button on the TIN Editing toolbar. The Set TIN Tags dialog window appears.
- Set the desired properties for the TIN tags to be modified.
Type— Choose either Triangle or Node to set the type of TIN property to edit.
Method—Choose the selection method based on the type selected.
Node selection methods Description closest node
The node tag of the closest node to the selection point is modified.
within polygon
The node tag of all the nodes within a digitized polygon are modified.
Triangle selection methods Description point within
The triangle selected is modified.
polygon intersect
The triangle tags of the triangles both completely and partially inside a digitized polygon are modified.
flood by tag
All contiguous triangles with the same tag as the one clicked on are modified.
flood flat area
All contiguous (near) flat triangles to the one clicked will have the tags modified.
Flat area tolerance— The triangle selection will stop when a triangle is encountered that exceeds this threshold. The flat area tolerance is in degrees.
This option is only valid when flood flat area is used as the selection method for triangles.
Within enforced region— If the selected triangle belongs to an area surrounded by hard/soft polygon then only the tags inside this area will be modified. If this option is not selected, then the propagation continues for all triangles with the same tag ("flood by tag") or for all flat triangles around the original selected triangle ("flood by flat area").
This option is only valid when either flood by tag or flood flat area are used as the selection method for triangles.
Tag—Set the new assigned tag value.
- Select the locations on the TIN surface for which to change either the node or triangle tags.