The default value is zero for a basic Channel.

The FitsChan class ignores this attribute.

The default value for an StcsChan is zero, which causes the entire STC-S description is written out by a single invocation of the sink function. The text supplied to the sink function will not contain any linefeed characters, and each pair of adjacent words will be separated by a single space. The text may thus be arbitrarily large and the StcsLength attribute is ignored.

If Indent is non-zero, then the text is written out via multiple calls to the sink function, each call corresponding to a single " line" of text (although no line feed characters will be inserted by AST). The complete STC-S description is broken into lines so that:

• the line length specified by attribute StcsLength is not exceeded

• each sub-phrase (time, space, etc.) starts on a new line

• each argument in a compound spatial region starts on a new line

If this causes a sub-phrase to extend to two or more lines, then the second and subsequent lines will be indented by three spaces compared to the first line. In addition, lines within a compound spatial region will have extra indentation to highlight the nesting produced by the parentheses. Each new level of nesting will be indented by a further three spaces.

Note, the default value of zero is unlikely to be appropriate when an StcsChan is used within Fortran code. In this case, Indent should usually be set non-zero, and the StcsLength attribute set to the size of the CHARACTER variable used to receive the text returned by AST_GETLINE within the sink function. This avoids the possibility of long lines being truncated invisibly within AST_GETLINE.

The default value for an XmlChan is zero, which results in no linefeeds or indentation strings being added to output text. If any non-zero value is assigned to Indent, then extra linefeed and space characters will be inserted as necessary to ensure that each XML tag starts on a new line, and each tag will be indented by a further 3 spaces to show its depth in the containment hierarchy.

The default value for a YamlChan is two. Only non-zero values in the range 1-10 are allowed.