Compiling-asn1-specifications.md

@@ -114,7 +114,9 @@ On the runtime side:
 - ECN is not supported either
 - some codecs for specific *String* types are not supported (mainly because Python does not 
   have support for them): TeletexString, VideotextString, GraphicString and GenericString,
-  all using the ISO-2022 encoding.
+  all using the ISO-2022 encoding
+- the runtime is not thread-safe: only a single thread must make use of an ASN.1 specification
+  at a time, otherwise, encoding / decoding values can get mixed
 
 
 ## How to