If there is a line or a point that the automatically skip options would skip, but it is required for you to be meshed, you can specify the entity to not be skipped. As an example, we will force to mesh the line number 43, in order to concentrate elements around point number 29, as it was done in section Assign size to points example.

Select Mesh->Mesh criteria->No skip->Lines, and select line number 43. Press ESC.
Select Mesh->Draw->Skip entities to display the entities that will and will not be skipped in different colors. As is shown in next figure, the line 43 will now not be skipped; the rest of the lines are unaffected, and GiD will either skip or mesh them according to the automatic criteria set in the preferences window.

Entities that will be skipped and not skipped in this configuration.

Select Mesh->Unstructured->Assign sizes on points. A window appears in which to enter the element size around the points to be chosen. Enter 0.1 and click Assign.
Select the point number 29. Press <Esc> to indicate that the selection of points is finished and Close the window.
Generate the mesh again with the default general mesh size.
The resulting mesh is depicted. A high concentration of elements around point number 29 can be appreciated. Note that there are nodes on line number 43 because we have forced not to skip this line.

Mesh using the automatic skip criteria, assigning sizes by chordal error and forcing an entity not to be skipped.

In this last example we have forced the mesher not to skip an entity, but it may be interesting in some models to allow the mesher only to skip a few entities, meshing almost all of them.
Unsetting the Skip entities automatically option in the preferences window, all the lines and points will be meshed except the ones set explicitly to be skipped using the Mesh->Mesh criteria->Skip option. In this case, no entity will be skipped automatically according to tangency with neighboring entities.
The next example shows how to work like this.

Select Mesh->Reset mesh data to reset all mesh sizes introduced previously. (A window opens advising that all the mesh information is going to be erased. Press Ok.).
Select Mesh->Mesh criteria->Skip->Lines, and select lines 48 and 53. Press <Esc>.
Generate the mesh with the default general mesh size.
The result is a mesh similar to the first test, but the smaller elements near the lines 48 and 53 do not appear because these lines are now skipped when meshing.

Mesh with some lines explicitily forced to be skipped.

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