Permanent Residence
As well, some countries apply differing policies on Permanent Residence. New Zealand's "Permanent Resident Visa" never expires, for example. However, Permanent Residence in many countries is conditional on showing "sufficient ties" to the country in question. This varies. The UK requires presence in the United Kingdom one full day every two years; Belgium is one full day per year (extended to 6 if the person holding Type B PR is residing in the EU); and Singapore requires permission to leave, and has a time limit on this permission (if either of these are ignored, PR expires)