Here are the descriptions associated to the each RMC error code.

• 0 - ERMSuccess: not actually an error.
• 1 - ERMErrGeneral: the RME encoutered a severe error during execution and managed to catch it.
• 2 - ERMErrPanic: the RME encoutered a really severe error and managed to catch it.
• 3 - ERMErrSystemRes: the RME encoutered an error while trying to access some local resource. Such local resource include memory...
• 4 - ERMErrNotFound: the RME encountered an error while trying to access a local or remote content. Error code was 404 before.
• 5 - ERMErrArgument: the RME encoutered a severe error during execution.
• 6 - ERMErrCorrupted: the RME read corrupted data from an URN. This error is raised when a file or server stream is corrupted, but the most frequent use case is when the RME reads a HTTP 200 response from a server with a HTML page giving a visual 404 error.
• 7 - ERMErrNotAvailable: the RME has requested an unavailable resource. This may happen when trying to access sound card.
• 8 - ERMErrNotSupported: The RME has attempted to use an unsupported format feature. RME raises this error when trying to read a non supported format (yet).
• 9 - ERMErrCompletion: not actually an error. Noone shall never se this.
• 10 - ERMErrTimeOut: deprecated error code.
• 11 - ERMErrMalformedURI: the RME has encountered a malformed URI during execution.
• 12 - ERMErrDNS: the RME has encoutered an error while resolving host names. Since this call is the first network when trying to access a remote content, it will be raised when there is a 'device level' issue accessing network: no modem, no SIM card, no APN configured or unproper operator agreement.
• 13 - ERMErrRequest: the RME has encoutered an error while sending a request to server. This is a detailled HTTP failure error code and general ERMErrNotFound error code may be raised instead.
• 14 - ERMErrOpenResource: the RME has encoutered an error while reading content from a server. This error is raised when the server sends an explicit '404' error code. This is a detailled HTTP failure error code and general ERMErrNotFound error code may be raised instead.
• 15 - ERMErrConnectRefused: the RME has encoutered an error while connecting to a server. This error is raised when the TCP connection is refused. This is a detailled HTTP failure error code and general ERMErrNotFound error code may be raised instead.
• 16 - ERMErrHttpHeader: the RME has received an invalid HTTP header while reading from an HTTP server. This is a detailled HTTP failure error code and general ERMErrNotFound error code may be raised instead.
• 17 - ERMErrHttpRequest: deprecated.
• 18 - ERMErrHttpResponse: the RME has received an invalid response while reading from an HTTP server. This is a detailled HTTP failure error code and general ERMErrNotFound error code may be raised instead.
• 19 - ERMErrHttpRedirect: the RME has encountered an invalid HTTP field for redirection. This is a detailled HTTP failure error code and general ERMErrNotFound error code may be raised instead.
• 20 - ERMErrPredictiveNetError: the RME has foreseen a future network error (e.g. because of offline mode) or because there is no SIM card.
• 21 - ERMErrNetConnection: the RME has encountered an error when establishing a network connection. This may append when a wrong APN has been selected or when device is out of network range.
• 22 - ERMErrNetConnectionCancel: the user has canceled the network connection
• 23 - ERMErrNetHttpNoSecureSupport: RM Engine has detected HTTPS is required and is not supported.
• 24 - ERMErrNetHttpInvalidCertificate: RM Engine has detected an invalid certificate has been returned by server.

You can also find this list in the Workbench Developer Help > Streamezzo Language Guide > Commands, on the page dediacted to registerError command.