|  | * 600 - 699 - Lucene Backend error codes | 
|  | 600: "Unable to read index" | 
|  | 601: "Unable to find index" | 
|  | 602: "Unable to add document to index" | 
|  | 603: "Unable to commit staged data to index" | 
|  | 604: "Unable to connect to database" | 
|  | 610: "Missing request parameters" | 
|  | 620: "Unable to generate JSON" | 
|  | 621: "Unable to parse JSON" | 
|  | 680: "Server is up and running!" | 
|  | 681: "Document was added successfully", document id | 
|  | 682: "Response time exceeded" | 
|  |  | 
|  | * 700 - 799 - Coral Deserialization errors | 
|  | 700: "No Query given" | 
|  | 701: "JSON-LD group has no @type attribute" | 
|  | 702: "Boundary definition is invalid" | 
|  | 703: "Group expects operation" | 
|  | 704: "Operation needs operand list" | 
|  | 705: "Number of operands is not acceptable" | 
|  | 706: "Frame type is unknown" | 
|  | 707: "Distance Constraints have to be defined as arrays" | 
|  | 708: "No valid distances defined" | 
|  | 709: "Valid class numbers exceeded" | 
|  | 710: "Class attribute missing" | 
|  | 711: "Unknown group operation" | 
|  | 712: "Unknown reference operation" | 
|  | 713: "Query type is not supported" | 
|  | 714: "Span references expect a start position and a length parameter" | 
|  | 715: "Attribute type is not supported" | 
|  | 716: "Unknown relation" | 
|  | 740: "Key definition is missing in term or span" | 
|  | 741: "Match relation unknown" | 
|  | 742: "Term group needs operand list" | 
|  | 743: "Term group expects a relation" | 
|  | 744: "Operand not supported in term group" | 
|  | 745: "Token type is not supported" | 
|  | 746: "Term type is not supported - treated as a string" | 
|  | 747: "Attribute is null" | 
|  | 750: "Passed notifications are not well formed" | 
|  | 760: "Exclusion is currently not supported in position operations" | 
|  | 761: "Class reference operators are currently not supported" | 
|  | 762: "Span references are currently not supported" (Not in use) | 
|  | 763: "Excluding distance constraints are currently not supported" | 
|  | 764: "Class reference checks are currently not supported - results may not be correct" | 
|  | 765: "Relations are currently not supported" | 
|  | 766: "Peripheral references are currently not supported" | 
|  | 767: "Case insensitivity is currently not supported for this layer" | 
|  | 768: "Attributes are currently not supported - results may not be correct" | 
|  | 769: "Overlap variant currently interpreted as overlap" | 
|  | 770: "Arity attributes are currently not supported - results may not be correct" | 
|  | 771: "Arbitrary elements with attributes are currently not supported" | 
|  | 780: "This query matches everywhere" | 
|  | 781: "Optionality of query is ignored" | 
|  | 782: "Exclusivity of query is ignored" | 
|  | 799: Unknown query serialization message (Arbitrary string) | 
|  |  | 
|  | * 800 - 899 - Virtual Collection Messages | 
|  | 802: "Match type is not supported by value type" | 
|  | 804: "Unknown value type" | 
|  | 805: "Value is invalid" | 
|  | 806: "Value is not a valid date string" | 
|  | 807: "Value is not a valid regular expression" | 
|  | 810: "Unknown document group operation" (like 711) | 
|  | 811: "Document group expects operation" (like 703) | 
|  | 812: "Operand not supported in document group" (like 744) | 
|  | 813: "Collection type is not supported" (like 713) | 
|  | 814: "Unknown rewrite operation" | 
|  | 815: "Rewrite expects source" | 
|  | 830: "Filter was empty" | 
|  | 831: "Filter is not wrappable" | 
|  | 832: "Filter operation is invalid" | 
|  | 850: "Collections are deprecated in favour of a single collection" | 
|  | 851: "Legacy filters need @value fields" | 
|  |  | 
|  | * 900 - 999 - Corpus Data errors | 
|  | 952: "Given offset information is not numeric" | 
|  | 953: "Given offset information is incomplete" |