area <-same_sides: area -> intReturns a bitmask for sides that have the same value on both arguments.
Implemented in the darkness of time for handling automatic layout. The
values of the mask are:
| Receiver | Argument | Value (octal) |
| top | top | 01 |
| top | center | 02 |
| top | bottom | 04 |
| center | top | 010 |
| bottom | top | 020 |
| bottom | center | 040 |
| bottom | bottom | 0100 |
| left | left | 0200 |
| left | middle | 0400 |
| left | right | 01000 |
| middle | left | 02000 |
| middle | middle | 04000 |
| middle | right | 010000 |
| right | left | 020000 |
| right | middle | 040000 |
| right | right | 0100000 |
The PCE/Prolog library file area.pl
defines these bitmasks.
