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    With the introduction of AutoCAD 2021 both the “Trim” and “Extend” commands have been enhanced to improve workflow and speed up the command process.
    In previous versions of AutoCAD, when using either of these commands, instead of selecting individual object to define either the cutting or boundary edges, by pressing “Enter” all objects within the drawing would be selected.

    This method of selecting objects when using the “Trim” and “Extend” commands can still be accomplished by selecting the sub command “Cutting Edges”, either from the command line or the right click menu, and then selecting the individual cutting or boundary edges.

    In AutoCAD 2021, once either of these commands are activated, all the objects within the drawing automatically become either cutting edges in the case of “Trim”, or boundary edges in the case of “Extend”, so saving the need to press “Enter”.
    Objects can be either “Trimmed” or “Extended”, depending on the initial command selected using the following options to select the objects:-
    • Pick individually using the cursor.
    • Hold down the left button to produce a free hand “Lasso” (sketch) line over the items.
    • Use the AutoCAD 2021 two-point fence selection function.
    • Using a “Crossing” window by either typing “C” and enter or selecting “Crossing” from the command line.
    • Or typing “F” to use the original “Fence” command.

    Selection methods shown in Figure 1. are being used with the “Trim” command.


    The resulting “Trim” is shown in Figure 2.


    The “Quick Trim” function will also work with boundaries that include “Hatch” patterns as shown in Figure 3.


    And can also be used to “Trim” “Hatch” patterns as shown in Figure 4.


    By changing the system variable “TRIMEDGES” to zero, each line of the “Hatch” pattern now becomes a cutting edge, as shown in Figure 5.


    Unfortunately, this function doesn’t currently seem to work with the “Extend” command.

    Holding down the “Shift” key will enable the command to be reversed, “Extend” in the case of “Trim”, and “Trim” in the case of “Extend”.

    If the 2020 and prior method of selecting objects for both trim and extend is preferred, by changing the system variable “TRIMEXTENDMODE” to zero, this will set the selection method back to the previous way of working.

    Alternatively, after activating either command, select the sub command “Mode” from the command line and then select “Standard”, as shown in Figure 3. 


    Or by using the right click menu as shown in Figure 4.