What does this icon in my notification window mean?

Question

Recently an icon has started to appear in my notification window. What does it mean ?

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Answer 1

Its shows that your phone is in Extended Standby Mode.

You can find it in Settings->PowerManagemnet

Extended standby mode increases the standby time by reducing the background activities when the phone is in standby mode.

Data will automatically be turned off and background activities will be stopped from waking up , while applications will also be prevented from syncing data.

You will still be able to receive calls and texts, while the calendar application and alarms will still feature normally. As soon as you unlock your smartphone it'll go returning to functioning normally.

Any ongoing downloads or bluetooth transfer will be allowed to complete and once completed data will be turned off.

Extended standby mode is replaced with Stamina Mode for Xperia running on Jellybean or higher

Source : SONY

Answer 2

This iS Battery STAMINA Mode.

With Sony’s power management setting called Battery STAMINA Mode, you can extend the standby time of your Xperia™ device by more than four times. With Battery STAMINA Mode turned on, the background activities of most applications are reduced when you turn off the screen.