This option enables you to have a external list of images this list of images can be generated by a server side page and then inserted into the image dialog windows of TinyMCE. The images can be to internal site images or external URLs.
Example of usage of the external_image_list_url option:
tinyMCE.init({ ... external_image_list_url : "myexternallist.js" });
Example of a external link list file: (myexternallist.js)
var tinyMCEImageList = new Array( // Name, URL ["Logo 1", "logo.jpg"], ["Logo 2 Over", "logo_over.jpg"] );