This routine decodes a SCUBA-style data specification. The data-spec will be of the form {$<$component$>$;$<$component$>$;...}, where components are one of the following:-

• B$<$index_spec$>$ - specifying bolometer indices

• P$<$index_spec$>$ - position indices

• S$<$index_spec$>$ - switch indices

• E$<$index_spec$>$ - exposure indices

• I$<$index_spec$>$ - integration indices

• M$<$index_spec$>$ - measurement indices

and the $<$index_spec$>$ is a list like, for example, 2,5:7,17 to select indices 2, 5 through 7 and 17. Alternatively, $<$index_spec$>$ can be $\ast$ which will select all data in that component coordinate. The data spec can be passed in as an array of data specs. The number is specified by N_SPEC. By default all components in a dataset are selected. Thus the empty data-spec {} will return all components selected. Example data-specs are:-

• "{} - select all data

• "{B7,12;P57}" - select data for bolometers 7 and 12 at measurement position 57

• "{S2;E1;I3:M2}" - select data for all bolometers in switch 2 of exposure 1 of integration 3 in measurement 2 of the observation

• "{B29}" - select all data for bolometer 29

• "{B29;E1}" - select data for bolometer 29 in the first exposure of each integration

The data-spec is case-insensitive and blanks are ignored.

Errors will occur:-

• If you attempt to select indices outside the dimensions input to the routine.

• If you attempt to select data both by position Pxxx and by switch Sxxx, exposure Exxx, integration Ixxx or measurement Mxxx.

• If you attempt to select by switch Sxxx when the SWITCH_EXPECTED flag is input .FALSE.

Output consists of a flag POS_SELECTED, to say whether or not the data were selected by position, and mask arrays that are set to 1 at the coordinate of selected data and 0 otherwise. Even if the data were not selected by position the POS_S array, which is the mask for the position coordinate, will be set correctly. Conversely, however, the MEAS_S, INT_S, EXP_S and SWITCH_S arrays, which are masks for the measurement, integration, exposure and switch will not be set to sensible values if the data are position selected.

CALL SCULIB_DECODE_SPEC (SPEC, DEMOD_POINTER, N_SWITCHES,N_EXPOSURES, N_INTEGRATIONS, N_MEASUREMENTS, N_POS, N_BOLS, SWITCH_EXPECTED, POS_SELECTED, POS_S, SWITCH_S, EXP_S, INT_S, MEAS_S, BOL_S, STATUS)

N_SPEC = INTEGER (Given)

SPEC( N_SPEC ) = CHARACTER$\ast$($\ast$) (Given)

DEMOD_POINTER (N_SWITCHES, N_EXPOSURES, N_INTEGRATIONS, N_MEASUREMENTS)

= INTEGER (Given)

N_SWITCHES = INTEGER (Given)

N_EXPOSURES = INTEGER (Given)

N_INTEGRATIONS = INTEGER (Given)

N_MEASUREMENTS = INTEGER (Given)

N_POS = INTEGER (Given)

N_BOLS = INTEGER (Given)

SWITCH_EXPECTED = LOGICAL (Given)

POS_SELECTED = LOGICAL (Returned)

POS_S (N_POS) = INTEGER (Returned)

SWITCH_S (N_SWITCHES) = INTEGER (Returned)

EXP_S (N_EXPOSURES) = INTEGER (Returned)

INT_S (N_INTEGRATIONS) = INTEGER (Returned)

MEAS_S (N_MEASUREMENTS) = INTEGER (Returned)

BOL_S (N_BOLS) = INTEGER (Returned)

STATUS = INTEGER (Given and Returned)

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