type Subnormal

              object --+                    
                       |                    
exceptions.BaseException --+                
                           |                
        exceptions.Exception --+            
                               |            
        exceptions.StandardError --+        
                                   |        
          exceptions.ArithmeticError --+    
                                       |    
                        DecimalException --+
                                           |
                                          Subnormal

Known Subclasses:

• Underflow

Exponent < Emin before rounding.

This occurs and signals subnormal whenever the result of a conversion or operation is subnormal (that is, its adjusted exponent is less than Emin, before any rounding). The result in all cases is unchanged.

The subnormal signal may be tested (or trapped) to determine if a given or operation (or sequence of operations) yielded a subnormal result.