The field Parameter

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2.3.2 The field Parameter

The field parameter is a string that specifies which field names or ids will be processed in the task or tool. The field selection expression consists of comma separated list of field specifications inside the string.

Field specifications can be literal field names, regular expressions or patterns (see § 2.3.1.1). Those fields for which the entry in the NAME column of the FIELD MS sub-table match the literal field name/regular expression/pattern are selected. If a field name/regular expression/pattern fails to match any field name, the given name/regular expression/pattern are matched against the field code. If still no field is selected, an exception is thrown.

Field specifications can also be given by their integer IDs. IDs can be a single or a range of IDs. Field ID selection can also be done as a boolean expression. For a field specification of the form ’>ID’, all field IDs greater than ID are selected. Similarly for ’<ID’ all field IDs less than the ID are selected.

For example, if the MS has the following observations:

MS summary:
==========
FIELDID   SPWID   NChan       Pol        NRows     Source Name
---------------------------------------------------------------
0          0      127         RR        10260     0530+135
1          0      127         RR        779139    05582+16320
2          0      127         RR        296190    05309+13319
3          0      127         RR        58266     0319+415
4          0      127         RR        32994     1331+305
5          1       1      RR,RL,LL,RR   23166     KTIP

one might select

  field = ’0~2,KTIP’          # FIELDID 0,1,2 and field name KTIP
  field = ’0530+135’          # field 0530+135
  field = ’05*’               # fields 0530+135,05582+16320,05309+13319

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