Symbol(axis) - Axis symbol

Description:

This attribute specifies a short-form symbol to be used to represent co-ordinate values for a particular axis of a Frame. This might be used (e.g.) in algebraic expressions where a full description of the axis would be inappropriate. Examples include "RA" and "Dec" (for right ascension and declination).

If a Symbol value has not been set for a Frame axis, then a suitable default is supplied.

The default Symbol value supplied for simple Frames is the string ``$<$ Domain$>$ $<$ n$>$ '', where $<$ n$>$ is 1, 2, etc. for successive axes, and $<$ Domain$>$ is the value of the Frame's Domain  attribute (truncated if necessary so that the final string does not exceed 15 characters). If no Domain value has been set, "x" is used as the $<$ Domain$>$ value in constructing this default string.

Specialised Frames (SkyFrame, SpecFrame,etc.) re-define the default Symbol value to be appropriate for the particular co-ordinate system being represented.

Type:

String.

Examples:

wcsattrib my_data set symbol(2) AR

This sets the Symbol for Axis 2 in the current Frame in the NDF called my_data, to the string "AR".

Notes:

• When specifying this attribute by name, it should be subscripted with the number of the Frame axis to which it applies.