Marker breaks the consoles into several parts to increase the displacements calculation accuracy for very long non-branched pipelines. See static analysis.
Add markers only if required to increase the displacement accuracy.
A marker can be placed at, for example, 500 meter spacing. A marker should not always be used for all models, but rather only in special cases when it is required to increase analysis speed and accuracy.
Typical market placement:
To insert an element, select the desired node and use: Insert > Insert Restraint > Marker
or press the 
toolbar icon.
To view properties of an existing element:
Double-click the element in the 3D view
Select the
element and press the 
toolbar icon