1 files changed, 24 insertions, 8 deletions
diff --git a/pyasn1/error.py b/pyasn1/error.py
index cb30033..4f48db2 100644
--- a/pyasn1/error.py
+++ b/pyasn1/error.py
@@ -7,33 +7,41 @@
 
 
 class PyAsn1Error(Exception):
-    """Create pyasn1 exception object
+    """Base pyasn1 exception
 
-    The `PyAsn1Error` exception represents generic, usually fatal, error.
+    `PyAsn1Error` is the base exception class (based on
+    :class:`Exception`) that represents all possible ASN.1 related
+    errors.
     """
 
 
 class ValueConstraintError(PyAsn1Error):
-    """Create pyasn1 exception object
+    """ASN.1 type constraints violation exception
 
     The `ValueConstraintError` exception indicates an ASN.1 value
     constraint violation.
+
+    It might happen on value object instantiation (for scalar types) or on
+    serialization (for constructed types).
     """
 
 
 class SubstrateUnderrunError(PyAsn1Error):
-    """Create pyasn1 exception object
+    """ASN.1 data structure deserialization error
 
     The `SubstrateUnderrunError` exception indicates insufficient serialised
-    data on input of a de-serialization routine.
+    data on input of a de-serialization codec.
     """
 
 
 class PyAsn1UnicodeError(PyAsn1Error, UnicodeError):
-    """Create pyasn1 exception object
+    """Unicode text processing error
 
     The `PyAsn1UnicodeError` exception is a base class for errors relating to
     unicode text de/serialization.
+
+    Apart from inheriting from :class:`PyAsn1Error`, it also inherits from
+    :class:`UnicodeError` to help the caller catching unicode-related errors.
     """
     def __init__(self, message, unicode_error=None):
         if isinstance(unicode_error, UnicodeError):
@@ -42,18 +50,26 @@ class PyAsn1UnicodeError(PyAsn1Error, UnicodeError):
 
 
 class PyAsn1UnicodeDecodeError(PyAsn1UnicodeError, UnicodeDecodeError):
-    """Create pyasn1 exception object
+    """Unicode text decoding error
 
     The `PyAsn1UnicodeDecodeError` exception represents a failure to
     deserialize unicode text.
+
+    Apart from inheriting from :class:`PyAsn1UnicodeError`, it also inherits
+    from :class:`UnicodeDecodeError` to help the caller catching unicode-related
+    errors.
     """
 
 
 class PyAsn1UnicodeEncodeError(PyAsn1UnicodeError, UnicodeEncodeError):
-    """Create pyasn1 exception object
+    """Unicode text encoding error
 
     The `PyAsn1UnicodeEncodeError` exception represents a failure to
     serialize unicode text.
+
+    Apart from inheriting from :class:`PyAsn1UnicodeError`, it also inherits
+    from :class:`UnicodeEncodeError` to help the caller catching
+    unicode-related errors.
     """