Mirroring creates a mirror image of objects. It is useful for creating symmetrical objects because you can quickly draw half the object and then mirror it rather than drawing the entire object.
You flip objects about an axis called a mirror line to create a mirror image. To specify this temporary mirror line, you enter two points. You can choose whether to delete or retain the original objects. Mirroring works in any plane parallel to the XY plane of the current UCS.
When you mirror text, attributes, and attribute definitions, they are reversed or turned upside down in the mirror image. To prevent this, set the MIRRTEXT system variable to 0 (off). By default, MIRRTEXT is on. If you turn it off, the text has the same alignment and justification as before the mirroring. Compare the following illustrations.
The MIRRTEXT system variable affects text that is created with the TEXT, DTEXT, ATTDEF, or MTEXT commands; attribute definitions; and variable attributes. Text and constant attributes within an inserted block are mirrored as a consequence of mirroring the entire block. These objects are inverted regardless of the MIRRTEXT setting. For more information about blocks and attributes, see Using Symbols (Blocks).