How to make arcs and offsets
From Opera Wiki
The management of arcs and offsets is done through the dimensioning function, i.e., by pressing the File:Dimension Key.png button found both in the Design Sheet and in the General Data pane of the type.
Fuorisquadra
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The Outline frame will close and you will be able to see the result of the operation on the type. The two function bars (horizontal and vertical) of the Quote function are, however, still active; therefore, to re-enter the Design Sheet, click on the button located to the right of the horizontal bar of the quote function. On the Design Sheet, the type will be as shown in the figure below:
Exit the Design Sheet with the File:X.png button and record the type in Archive.
Archi
In the Design Sheet click on the File:Adarco.png button. The Arch Data frame will open; upon entering this frame the program proposes the creation of the round arch. Conversely, if your need is to create a segmental arch, click on the 
button; the drop-down for the arch type will open.
N.B: If you have chosen the segmental arch, the box will be activated so that you can determine the height of the radius
Now press the button to confirm the operation and re-enter the Design Sheet, the type will appear to you as the following figures show. In either case, exit the Design Sheet with the File:X.png button and record the type in the Archive.
