I think examples would be good

C:\>perl -le " print for w0rd => _w0rd => -w0rd => 07 => 1 "
w0rd
_w0rd
-w0rd
7
1

C:\>perl -le " print for 0word => 1 "
syntax error at -e line 1, near "0word"
Execution of -e aborted due to compilation errors.

C:\>perl -le " print for 08 => 1 "
Illegal octal digit '8' at -e line 1, at end of line
Execution of -e aborted due to compilation errors.
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