Flashing data.img in a zip w/o wiping /data/sdcard

Hello xda!
I made a rom but it needs to flash /data partition too. So I have to edit updater script.
When I look at it, there is something like this:

Code:

---

show_progress(0.750000, 0);
ui_print("Installing system image...");
package_extract_file("system.img", "/dev/block/bootdevice/by-name/system");

---

If I change "system"s with "data" would it flash data.img?
Like this:

Code:

---

show_progress(0.750000, 0);
ui_print("Installing DATA");
package_extract_file("data.img", "/dev/block/bootdevice/by-name/data");

---

Is this data.img going to flash without any errors?
would this wipe my sdcard? (my sdcard is in /data/sdcard)
If yes, how can I do it w/o wiping it?



Sorry for my bad english :D Waiting for answers

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