”Scan intent” selection is based on the entries in the "OBS_MODE" column of the "STATE" sub-table, as described in the Railroad diagram format in Table 7. The main table of a Measurement Set has the "STATE_ID" column containing the row number of the "STATE" sub-table appropriate for each row in the main table. The "OBS_MODE" column of the STATE sub-table contains strings describing the observational intent. These intents are referred to as ”scan intents” and the scan-intent expressions in the MSSelection module can be used for data selection based on these intents.
The scan-intent selection expression is a comma-separated list of specifications. Each specification can be a string (section 1.4) , an integer or an integer range (section 1.2). As in other such expressions, a range [N0,N1] can be specified as N0~N1 (see Section 1.2). String (section 1.4) can be regular expressions or patterns or quoted-strings for as-is matching (see Section 1.4).
A single scan can have multiple scan-intents represented by a comma-separated list of strings like "CALIBRATE_BANDPASS.UNSPECIFIED,CALIBRATE_AMPLI.UNSPECIFIED". Each of these comma-separated components are referred to as the scan-intent components. All string specifications in scan-intent expression are matched against each of these comma-separated components. Scans with any of the scan-intent components matching the string(s) in the scan-intent expression are selected. E.g. scanintent=⋆CAL⋆, ⋆BAND⋆ will select all scans which have the strings "CAL" or "BAND".
To allow selection based on scan-intent components, scan-intent selection specifications can also be ampersand-separated ('&') list strings. Only those scans, at least one scan-intent components of which match all the ampersand-separated components are selected. E.g. scanintent=⋆CAL⋆ & ⋆BAND⋆ will select only those scans the intent strings of which contain the strings "CAL" and "BAND". See Section 8.2 for more examples.
Table 8 shows an example-table of scan-intents. Table 9 shows a list of some scan-intent selection expressions and the corresponding list of selected scan numbers from Table 8.
|Scan No.||Scan-intent strings|
|2||CALIBRATE_BANDPASS, CALIBRATE_AMPLI, CALIBRATE_PHASE|
|⋆PHASE||0,2||Matches CALIBRATE_PHASE but|
|⋆AMPLI, ⋆PHASE||1,2||⋆AMPLI matches CALIBRATE_AMPLI;|
|⋆PHASE matches CALIBRATE_PHASE|
|⋆AMP⋆||1,2,3||⋆AMP⋆ matches CALIBRATE_AMPLI and|
|⋆BAND & ⋆PHASE||0,2||⋆BAND and ⋆PHASE are simultaneous present|
|for scans 0 and 2 only|
|AMP⋆ & ⋆PHASE⋆||3||⋆PHASE⋆ matches scans 0,2,3. AMP⋆ matches|
|only scan 3.|
|⋆BAND & ⋆PHASE⋆ & ⋆AMP⋆||2||Only scan that matches ⋆BAND and|
|⋆PHASE⋆ and ⋆AMP⋆ is scan 2|
|⋆BAND & ⋆PHASE⋆, AMPLI⋆||0,2,3||⋆BAND & ⋆PHASE selects scans 0,2.|
|AMPLI⋆ selects scan 3|