# Tube Point: about

## Tube Points

Tube Points are created by the user manually by specifying their coordinates in a coordinate system for definition (see Coordinate system: about).

## Units of the unique coordinate system

The units of the global coordinate system of the project are by default the millimeter (length units) and the degree (angle units).

## Parameter setting

The Tube Point coordinates can be defined using algebraic expression. The algebraic expression can contain:

- constants
- geometric parameters (created beforehand)
- basic mathematical functions using operators : +, -, *, /, ( )
- usual mathematical functions admitted by FORTRAN

The mathematical functions are described in section Functions.