| `Max_buffer_size |
| `Unexpected_eoi |
| `Malformed_char_stream |
| `Unknown_encoding of string |
| `Unknown_entity_ref of string |
| `Unknown_ns_prefix of string |
| `Illegal_char_ref of string |
| `Illegal_char_seq of string |
| `Expected_char_seqs of string list * string |
| `Expected_root_element |