The service interval, given in days (as integer), when this part has to be serviced again.
<boots>, <buoyancycontroldevice>, <camera>, <compass>, <compressor>, <divecomputer>, <fins>, <gloves>, <knife>, <lead>, <light>, <mask>, <rebreather>, <regulator>, <scooter>, <suit>, <tank>, <variouspieces>, <videocamera>, <watch>
(see also <equipment>, and above listed parts e.g.)
<!-- part needs a yearly service -->
<serviceinterval>365</serviceinterval>