Update PublishingImages using list.asmx

It takes from me too long time before success update PublishingImage Column using list.asmx.
We should pass value relative url with alt separated by comma. This is also applied for url, lookup, or user.
Check example below:

string xml = ""+         ""+         "    1"+         "    http://www.pub.com/publishingimages/test.jpg, test"+         "+ "       ";