Runtime error messages that appear in ESL are, by default, in English. They are maintained in an external file, EslErr.txt. This file is in a binary format is supported by the ESL Message Manager development tool (EslMsgMgr). Only the text of the messages can be amended or translated into a different language. The symbols and parameters cannot be altered, including the order of the parameters within the message text.

As the external message file is specified within the ESL configuration file, using the "ESLERR" parameter, it is recommended that the original file is kept and alternate versions given a filename appropriate to the language used within the message text.