Add new or missing materials to the list of materials available when drawing.
Problem: You can see material A106 B on the list, but not A106 A.
Select Edit, Master Files, Material Categories as shown:
Put the focus on row C, Carbon Steel Pipe.
Select Utilities, Edit Materials for Carbon Steel Pipe (or press F3).
You need to find an empty row to use for A106 A, so click Show Unused Rows.
Select an appropriate unoccupied row, such as row U as shown.
With the focus on row U, select Edit, Edit Description.
Enter the new description as shown.
With the focus still on row U, press the spacebar to set the In Use flag.
Press OK. The A106 A material is now available for selection as shown below.