The characters 'l' (which is lowercase 'L') and 'O' (which is uppercase 'o') should not be the only characters used in the identifier, because this would make them visually similar to numeric literals.
Hide source code
# Identifiers should not be composed of 'l' and 'O' characters only
foreach file [getSourceFileNames] {
foreach t [getTokens $file 1 0 -1 -1 {identifier}] {
set value [lindex $t 0]
if [regexp {^(l|O)+$} $value] {
report $file [lindex $t 1] "identifier should not be composed of only 'l' and 'O'"
}
}
}