It's a well-known indicator that shows maximal and minimal prices (and average values) of the last n bars.
Translated from Russian by MetaQuotes Software Corp.
Original code: https://www.mql5.com/ru/code/85
Here is a simple example that shows how to download page(file) from Internet using the library wininet.dll.sChartsSynchroScroll
The script provides a synchronous scrolling for all charts opened in the client terminal.