> For the complete documentation index, see [llms.txt](https://eako-capital.gitbook.io/eako-user-guide/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://eako-capital.gitbook.io/eako-user-guide/barrier-options/time-aspect.md).

# Time Aspect

How the Barrier is monitored

### Continuous (otherwise known as "American" style barrier)

Refers to the time aspect of the barrier condition.  A continuous barrier means that the option will be knocked in (knocked out) if the spot rate trades at or through the barrier at any time prior to expiry.

### Window

Also refers to the time aspect of the barrier condition.  A window barrier means that the option can only be knocked in (knocked out) during a predetermined specified period.

The main types of window barrier are:

Forward Barrier - Forward Start means that the barrier is inactive for the first part of the option's term and can only be triggered after an agreed date till expiry.

Partial Barrier - Means that the barrier is active only for a period from the transaction date to an agreed date and can only be triggered during this period.

### "European" style barrier

Means that the barrier condition is only active at expiry of the option.