## spectrum, fragment mass error units## SyntaxThe value for this parameter is an ASCII string, with two possible values: Daltons or ppm ## Notes- If this parameter is not present or set to a unexpected value, a default value is substituted.
- No error message is generated when a bad value is used for this parameter.
- Interpretation of this value depends on the value set for spectrum, fragment mass type.
## DescriptionThe value for this parameter alters the interpretation of the value for the parameter named spectrum, fragment mass error. The interpretation of the two values are described below. - Daltons: If this value is set, then the value of
spectrum, fragment mass error (T
_{f}) is simply interpreted as a mass and the condition for a fragment ion to be considered found is given by: | m - p | < T_{f} where m is a mass in a spectrum and p is the calculated mass of a peptide fragment. - ppm: If this value is set, then the value of T
_{f}is interpreted as representing parts-per-million (commonly used in mass spectrometry to express precision), altering the condition for a fragment ion to be as follows: | m - p | < m(T_{f}x 10^{-6})
see also: spectrum, fragment mass error | spectrum, fragment mass type | X! TANDEM API description project |