Basic syntax errors
These are simple errors that Vyatta NOS detects through its configuration data model — that is, a conflict with something that we've modeled in YANG.
The nature of these errors is such that Vyatta NOS can detect and report them as soon as we try to submit a problematic command string in the CLI.
These errors are usually easy to troubleshoot because you know that the problem is with the command string that you just tried to submit, and because the error messages tend to be self-explanatory.
Syntax error example: An invalid keyword in a configuration path
Here we enter a keyword that is invalid for the configuration path.
user@system# set policy qos banana-split Configuration path: policy qos [banana-split] is not valid  user@system#
banana-split is not a valid entry in this configuration path. Vyatta NOS expects a valid term, as defined in YANG — in this case, a keyword like
Syntax error example: An invalid value in the configuration path
Here we enter an invalid argument — specifically, an invalid value in a keyword-value pair.
user@system# set policy qos name abc/123 Configuration path: policy qos name [abc/123] is not valid Only alpha-numeric name allowed Value validation failed Set failed  user@system#
Symbols like the forward slash
/ are not allowed in the value of this keyword-value pair. Vyatta NOS expects a valid value, as defined in YANG — in this case, the value should contain only alpha-numeric characters.