## Parallelism/Perpendicularity

Parallelism and perpendicularity constraints are set for pairs of lines
or segments using the following methods:

```cpp
constraint_item GCE_AddParallel(GCE_system gSys, geom_item g[2])
```

```cpp
constraint_item GGCE_AddPerpendicular(GCE_system gSys, geom_item g[2])
```

Methods accept the following initial data: **gSys** is the geometric
constraint system, **g**\[2\] is a pair of straight-line curves. The
methods return a descriptor of a geometric constraint registered in the
**gSys** system.