What sources of income are acceptable for Italy’s elective residence visa?

I understand that applicants of Italy’s elective residence visas must prove to have access to legitimate income from sources other than work. What types of sources are acceptable?

Answers

On Alessia Ajelli answered:

Resources must derive from prolific revenues (annuities, pensions), property ownership and stable economic-financial activities, but NOT from employment (it must be a “passive income”). Resources can derive

On Marco Mazzeschi answered:

Resources must derive from prolific revenues (annuities, pensions), property ownership and stable economic-financial activities, but NOT from employment (it must be a “passive income”). Resources can derive

On Carlo Umberto Rossi answered:

Resources must derive from prolific revenues (annuities, pensions), property ownership and stable economic-financial activities, but NOT from employment (it must be a “passive income”). Resources can derive