server-side includes provide important information on web pages hosted by classic ASP web sites.
The #flastmod include prints the date when the file was last modified. The #fsize include prints the size of the specified file.
When you apply these includes to a web site that allows users to download files, they allow users to check and see whether a file is new, and also the size, so that the user can estimate how long the download will take.
Also, these commands are dynamic. This means that if the file size changes or the last modified date changes, the files are updated automatically.
The file available for download is
<a href="download.zip">Download.zip</a>, its size is
<!--#fsize file="download.zip"-->. The file was last updated
on <!--#flastmod file="download.zip"-->