| DSSbitType | error  | 
|   | Column must be an integer for bit mask filters   | 
| BlockSpec | error  | 
|   | File/block specification is not in a format supported by the data subspace.
The deprecated forms using [] or + cannot be used with the data subspace.   | 
| DssRefClash | error  | 
|   | The filter references different blocks (referring
to different block filters) with the same name. The data subspace cannot
be written.   | 
| DssBlockClash | warning  | 
|   | Name clash while writing Data Subspace. Block already 
exists in output data set.
 corrective action: The block is renamed.   | 
| NoFilter | error  | 
|   | Filter not found in data subspace component.   | 
| NoRange | error  | 
|   | No range information available for this filter type.   | 
| DSextentType | error  | 
|   | The filter is not of a type for which a determination 
of the extent is supported (eg. a mask filter)   | 
| DSextentGTI | error  | 
|   | The argument of the extent command does not correspond to
the name of the GTI filter being queried.   | 
| DSextentRange | error  | 
|   | The argument of the extent command does not correspond to
the name of the Range filter being queried.   | 
| DSextentRegion | error  | 
|   | The argument of the extent command does not correspond to
the name of one of the components of the Region filter.   | 
| NoMask | error  | 
|   | No bit mask information available for this filter type.   | 
| NoRegion | error  | 
|   | No region information available for this filter type.   | 
| NoBlock | error  | 
|   | No block information available for this filter type.   | 
| BlockTypeGti | error  | 
|   | Block type is not compatible with the gti filter type.   | 
| BlockTypeMask | error  | 
|   | Block type is not compatible with the mask filter type.   | 
| DSSblockType | error  | 
|   | The filter type for the specified block could not be determined.   | 
| MaskType | error  | 
|   | Mask array is not of a supported data type.   | 
| DSStype | error  | 
|   | Incompatible data types for DSS and column specifications.   | 
| BlockTypeRange | error  | 
|   | Block type is not compatible with the range filter type.   | 
| RangeType | error  | 
|   | Columns are not of a supported data type for a range specification.   | 
| BlockTypeRegion | error  | 
|   | Block type is not compatible with the region filter type.   | 
| ColumnClash | error  | 
|   | Data subspace filter name and column name are not consistent.
Cannot write data subspace.   | 
| BadRegionFilter | error  | 
|   | A data subspace filter with a region specification has been 
found.  This type of filter is not supported.   | 
| BitVol | warning  | 
|   | Cannot calculate volume for
a bit mask filter.
 corrective action: Zero volume returned for this filter type.   | 
| RangeVol | warning  | 
|   | Cannot calculate volume of 
a range specification with only one limit.
 corrective action: Zero volume is returned for this filter.   | 
| DSStypeTruncate | warning  | 
|   | Real-valued ranges are used for an integer-valued column.
 corrective action: Real-valued ranges are truncated to integers.   | 
| DssSyntaxError | error  | 
|   | The parser was not able to parse the selection expression so as
to convert it to a data subspace specification.   | 
| ArithmeticException | error  | 
|   | An illegal arithmetic operation was specified in the selection
expression.   | 
| MaskSpecOffset | error  | 
|   | A mask filter was specified with a non-zero offset.  The data subspace
is only able to store masks with a zero offset.   | 
| DssNameMismatch | error  | 
|   | Name of coordinate axes in region filter do not match that of 
preceding filter in same component.  See section on ``Tips and Grouping of Region Functions''
to find out how to avoid this error.   | 
| BitMaskTesting | error  | 
|   | Bit mask filter must be tested against ``== 0''. This syntax, along with
the equivalent syntax ``!(mask!==0)'', are the only two that are supported.   | 
| DssFitsWrite | warning  | 
|   | The data
subspace indexing has become to large to fit into keywords of the from nDSVALn (keywords can
be on more than 8 characters).  Thus no filter information can be written to the FITS header
for the filter in question.
 corrective action: No data subspace information is written for the given filter.   |