This data item defines a line in space.
Other data items can check if nodes are located on this geometry.
Coordinates of the end points are denoted
by *x_0*, etc.. In 1D, only the -coordinates should be specified,
etc.. All **node** within a distance *radius* are considered
to be part of the line.

In the example, a line in 2D space is defined and is used by a
**convection_geometry** record (nodes located on the line will convect heat)

...

geometry_line 2 1. 0. 1. 1. 0.01

...

group_condif_convection_geometry 0 -geometry_line 2

...

tochnog 2001-09-02