You might design your label templates to print text objects using internal printer fonts. These are the fonts that are stored in your printer's memory. If you try to print such labels to a different kind or printer, the selected internal fonts might not be available. The new printer probably supports an entirely different set of internal fonts. The font layout might be similar in such case, but is available under a different name.
Font mismatch might also occur if the Truetype font that you are using on your labels is not installed on the computer on which you run Designer to design and print labels.
You can configure Designer to automatically replace the fonts used on the label with compatible fonts. I such case, Designer maps and replaces the fonts using their names. If the original font is not available, Designer uses the first available replacement font defined in the mapping table.
If there are no suitable replacement fonts, Designer uses the Arial Truetype font.
After configuring font replacement, mapping rules execute when you change the printer for your label.