code: public void checkZipCode(String zipcode) throws CmsIllegalArgumentException {
  
          if (!CmsStringUtil.validateRegex(zipcode, ZIPCODE_REGEX, true)) {
              throw new CmsIllegalArgumentException(Messages.get().container(Messages.ERR_ZIPCODE_VALIDATION_1, zipcode));
          }
      }
docs: That means, the parameter should only be composed by digits and standard english letters.<p>
  
  @see org.opencms.security.I_CmsValidationHandler#checkZipCode(java.lang.String)