A and B

E-ACCUMULATE, Coordinate systems are not compatible
LAS, SUM or ACCUMULATE commands. Two observations had different coordinate systems and could not be added.
User action : Convert them to a common coordinate system, or use the SET NOMATCH command to turn off position checking.

E-ACCUMULATE, Different calibrations
LAS, SUM or ACCUMULATE commands. Two observations were done with different major calibration parameters (Beam Efficiency and possibly Forward Efficiency) and could not be added.
User action : May be they were not on the same temperature scale. The weighting (and values) is incorrect in such a case. Modify the corresponding calibration parameter and retry. You may bypass this calibration checking by using command SET CAL OFF.

W-ACCUMULATE, Different reference channels R: <Real> T: <Real>
LAS, SUM or ACCUMULATE commands. Two spectra were added with the ALIGN mode CHANNELS, but had different reference channels, and hence possibly different velocity or frequency scales.
User action : Check if these spectra were to be added. If you want to add them and preserve a common velocity (or frequency) scale, use the ALIGN mode VELOCITY (resp. FREQUENCY).

W-ACCUMULATE, Different resolution R: <Real> T: <Real>
LAS, SUM or ACCUMULATE commands. Two spectra were added with the ALIGN mode CHANNELS, but had different resolutions and hence possibly different velocity or frequency scales.
User action : Check if these spectra were to be added. If you want to add them and preserve a common velocity (or frequency) scale, use the ALIGN mode VELOCITY (resp. FREQUENCY).

W-ACCUMULATE, Different rest frequencies R: <Real> T: <Real>
LAS, SUM or ACCUMULATE commands. Two spectra were added with the ALIGN mode CHANNELS or VELOCITY, but had different rest frequencies and hence possibly different velocity or frequency scales.
User action : Check if these spectra were to be added. If these spectra correspond to the same molecular line, use the MODIFY FREQUENCY to reset a common velocity scale and the ALIGN mode VELOCITY before adding them.

W-ACCUMULATE, Different velocities R: <Real> T: <Real>
LAS, SUM or ACCUMULATE commands. Two spectra were added with the ALIGN mode CHANNELS or FREQUENCY, but had different velocities and hence possibly different velocity or frequency scales.
User action : Check if these spectra were to be added. If these spectra correspond to the same object, use the MODIFY VELOCITY to reset a common rest frequency scale and the ALIGN mode FREQUENCY before adding them.

W-ACCUMULATE, Drift not aligned in position
LAS, SUM or ACCUMULATE commands. Two continuum drifts were added but are not coincident in position.
User action : Select POSITION alignment using command SET, and retry.

W-ACCUMULATE, Origin table overflow
LAS, SUM or ACCUMULATE commands. Too many spectra were added and the list of original scan numbers is full. Scan numbers of any other added spectrum will be lost.
User action : none. The spectrum still contains the sum the all desired spectra, only the list is wrong.

E-ACCUMULATE, Positions are not compatible
LAS, SUM or ACCUMULATE commands. Two spectra have different positions and have not been added.
User action : If you want to add them, use the SET NOMATCH command before.

E-ACCUMULATE, <String> ranges do not intersect
LAS, SUM and ACCUMULATE commands. Two spectra were to be added with the ALIGN mode specified by <String> and INTERSECT mode, but do not overlap.
User action : what do you want to add ?...

W-ACCUMULATE, Spectra not aligned in sky frequency R: <Real> T: <Real>
LAS, SUM and ACCUMULATE commands. Two spectra were added with ALIGN mode CHANNELS, but have a different sky frequency scale.
User action : use the SET ALIGN FREQUENCY if you want to preserve a common frequency scale.

E-ACCUMULATE, Too many channels requested
LAS, SUM and ACCUMULATE commands. Two spectra were added with ALIGN mode COMPOSITE, but the final spectrum requires more channels than reserved in the program.
User action : most likely you are trying to make a composite spectrum with two unrelated frequency bands, such as CO and HCN... Note also that making composite spectra is not necessary to plot a few GHz from a spectral survey.

E-ADD, Cannot add Continuum with Line data.
LAS, ACCUMULATE command: The two observations are not of the same kind. SUM command: The index contains observations of different kinds.
User action : It is time to get some rest and a cup of coffee...

W-ADD, Gives sum of spectra for EQUAL weight
LAS, ACCUMULATE command: This command gives the sum of the spectra, not the average.
User action : This behaviour is consistent with that of SUM which gives the average over the index. Using several ACCUMULATE commands, and then dividing the final result by the number of added observations yields the same result as SUM.

W-ADD, Still experimental for Continuum
LAS, ACCUMULATE and SUM commands.
User action : Poor guinea pig... Do not worry too much, it usually works fine, but we would appreciate receiving detailed comments if you find something bizarre.

E-BASE, Insufficient memory for work space
LAS, BASE command. The work space to compute the best fit polynomial could not be dynamically allocated because the program exhausted its virtual memory quota.
User action : i) clear any plot and restart. ii) run CLASS in a single process (not from a sub-process). iii) Ask your system manager to extend the virtual memory limit.

E-BASE, No line window
LAS, BASE command. No line window has been defined.
User action : define one or more windows using the SET WINDOW command.

E-BASE, No valid baseline
LAS, BASE command : the windows covers the full spectrum and leave no channels to compute the baseline
User action : define windows which do not cover the spectrum, or (if possible) compute the baseline from another backend and use the command BASE LAST to apply it to this spectrum.

E-BASE, Sinus not converged
LAS, BASE command with SINUS method. The minimization routine failed to converge to a valid solution.
User action : The solution may still be sensible, look at it. If not, retry with different guesses.