| SUCCESS | Indicates that the operation completed successfully. 
DESIGN NOTE: This value must be equal to zero to ensure that: if (returnCode)returns true in case of an error, false otherwise. | 
| UNKNOWN | An unknown error has occured. | 
| ILLEGAL_ARGUMENT | Indicates that a method has been passed an illegal or inappropriate argument. | 
| NOT_SUPPORTED | The optional operation is not supported by the implementation. | 
| OUT_OF_MEMORY | Could not allocate memory to perform the operation. | 
| INVALID_STATE | Indicates that we cannot call this method at this point in time. | 
| FILE_NOT_FOUND | Indicates that the specified file could not be found. | 
| PENDING_DATA | Indicates that no data is currently available but more is expected to arrive in the future. | 
| END_OF_STREAM | Indicates that the end of stream has been reached. | 
| SOCKET_IO_ERROR | Indicates that a socket error happened. | 
| SOCKET_CLOSED | Indicates that the socket was closed | 
| UNKNOWN_MODULE | Indicates that a library could not be loaded | 
| UNKNOWN_SYMBOL | Indicates that a library does not contain a specific symbol | 
| NO_MATCH | Indicates that the specified search criteria did not yield any results. | 
| OPEN_ERROR | Indicates an error occurs while opening a file or socket. | 
| READ_ERROR | Indicates an error occured while reading a file or socket. | 
| WRITE_ERROR | Indicates an error occured while writing to a file or socket. | 
| ARRAY_INDEX_OUT_OF_BOUNDS | Indicates that an array index was either negative or greater than or equal to the size of the array. | 
| GRAMMAR_SLOT_FULL | Indicates that the grammar slot is full and no further items may be added to it. | 
| HOMONYM_COLLISION | Indicates that an item cannot be added into a grammar slot because another item with the same pronunciation already resides in the slot. | 
| ALREADY_LOCKED | Indicates that the mutex or condition variable is already locked by someone else. | 
| THREAD_ERROR | Indicates that the thread-related operation has failed. | 
| TIMEOUT | Indicates that the previous operation has timed out. | 
| AUDIO_DRIVER_ERROR | Indicates that an error occured when invoking an audio driver function. | 
| AUDIO_ALREADY_IN_USE | The audio passed in as an argument is already in use by another module. | 
| OVERFLOW_ERROR | Indicates that the operation failed because it would have caused a variable or buffer to overflow its maximum value or capacity. | 
| UNDERFLOW_ERROR | Indicates that the operation failed because it would have caused a variable or buffer to underflow its minimum value or capacity. | 
| PARSE_ERROR | Could not parse a request coming from the server. | 
| SPEECH_SERVER_UNAVAILABLE | The network speech server is not available. | 
| SERVER_BUSY | The network server is busy. | 
| SERVER_SHUTTING_DOWN | The network server is shutting down | 
| GRAMMAR_LOAD_FAILURE | Unable to load the grammar. | 
| INVALID_URL | The specified URL is invalid. | 
| GRAMMAR_NOT_DEFINED | No grammar defined. | 
| INVALID_PARAMETER_NAME | the parameter you are tyring to set/get is invalid. | 
| INVALID_PARAMETER_VALUE | the value for the parameter you are tyring to set is invalid. | 
| UNSUPPORTED_CODEC | This codec is not supported | 
| SERVER_PING_MISSED | We did not receive the ping request from the server. The server or the network connection must be down. | 
| MAXIMUM_BOUND | Return codes having this value or greater are invalid. |