; SPECTRAL
;---------------------------------------------------------------
;! Flag to indicate whether an operation is spectral or continuum
;# ADVERB CALIBRATION SPECTRAL
;-----------------------------------------------------------------------
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;-----------------------------------------------------------------------
SPECTRAL  LLLLLLLLLLLLUUUUUUUUUUUU CCCCCCCCCCCCCCCCCCCCCCCCCCCCC
----------------------------------------------------------------
SPECTRAL
Type: Scalar
Use:  To tell a task whether it should do some operation in a spectral
      chsnnel-dependent fashion or in a channel-independent fashion.
      SPECTRAL > 0 => channel-dependent methods hould be used.

Default: <= 0 => False  => do continuum methods
         >  0 => True   => do spectral methods

Tasks:
  PCAL......Computes antenna-based polarization leakage terms and,
            optionally, also determines source polarization (Q, U, V).
            SPECTRAL false selects the familiar IF dependent solution
            which is stored in the antenna and source tables.
            SPECTRAL true selects a channel-dependent solution which
            is stored in PD (leakage) and PS (source) tables whic
            resemble bandpass tables.
  RLDIF.....Determines Right minus Left phase difference, corrects
            cal files
  TRUEP.....Determines true antenna polarization from special data
            sets.
  XYDIF.....Find/apply X minus Y linear polarization phase difference
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