The principle use of this function is in decoding user-supplied input which contains formatted coordinate values. Free-format input is supported as far as possible. If input is ambiguous, it is interpreted with reference to the Frame's attributes (in particular, the Format string associated with the Frame's axis). This function is, in essence, the inverse of astFormat.
Examples of acceptable SkyFrame input formats (with interpretation in parentheses) include:
AST A Library for Handling World Coordinate Systems in Astronomy