Multi-purpose display-spec slot creation utility.
| 1: | In text, set the display meta-bit. |
| 2: | In a display-form expression, usually the formatting commands for display, insert a dislay-form child specifier, i.e., <[?]:[prompt]: * |Other>. |
| 3: | On a normal term, typically in the argument places of the model for the display form, insert the display template for terms. |