The two examples of use of the LOG_MAKEPRI macro in the manual for 2.16 (and earlier) are broken. The facility macros LOG_USER, ..., LOG_LOCAL1, ... already contain a left-shift of 3, so to use these macros in LOG_MAKEPRI (which also makes a shift), that shift has to be undone by using the LOG_FAC macro. The example at the end of 18.2.2 would then be something like

    syslog (LOG_MAKEPRI(LOG_FAC(LOG_LOCAL1), LOG_ERROR),
            "Unable to make network connection to %s. Error=%m", host);

Alternatively, the documentation could drop mentioning the LOG_MAKEPRI macro at all and simply instruct people to OR the facility and priority, resulting in the much simpler

    syslog (LOG_LOCAL1 | LOG_ERROR,
            "Unable to make network connection to %s. Error=%m", host);

(Alternatively, this is a bug against the LOG_MAKEPRI macro, which should simply do exactly this, but this would break code which uses the LOG_FAC macro.)