| spectrum, fragment mass error unitsSyntaxThe 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 (Tf) is
simply interpreted as a mass and the condition for a fragment ion to be considered found is
given by:| m - p | < Tf
 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 Tf 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(Tf x 10-6)
 
 see also: spectrum, fragment mass error  |
spectrum, fragment mass type |
 
 X! TANDEM API description project
 |