Folderinfo.bns

folderinfo.bns is a script file.

You can found one inside the scripts/challenges and scripts/advanced_chambers folders in portal_content.gcf

It's a pretty usefull file if you want to make/customize your own BonusMap package.

Script sample

"Package_Name"
{
	"image"		"Folder_Name/TextureName"
	"comment"	"This map pack is the best one"
	"lock"		"0"
}

Package_Name : the name of your package, that's will be displayed on the bonus map selection menu with 'Challange' and 'Advanced'
image : A path to a thumbnail thats represent your package. Path is materials/vgui/FolderName/TextureName Where TextureName is the name of the vmt file. If you let this value empty, a default folder picture will be used.
comment : a comment about your map pack.
lock : Should be 0 to unlock your mappack, if you set it to 1 nobody can play it. (If someone know any unlock script/entity...)

How to use

The best way is to make a new folder inside your portal/maps folder like : portal/maps/MyBonusMapPack.
Put your folderinfo.bns inside it with your bonus map script and/or challenge scripts files.
You can put your maps files (.bsp) in it if you want, because you can locate them to diffrent location by the bonus map script or challenge scripts.