Marks are made in chalk, flour or some other medium, dependiing on terrain and weather. The Hares for each Run decide how to mark the trail. A balance between sparse use and keeping everyone informed should be maintained. All marks should be clearly visible at key points to avoid anyone getting lost or misinterpreting the trail.

On Trail Arrow
 
If you see this mark, in chalk on walls, on a road or other hard surfaces you will know that you are 'On Trail'. A shout of 'On On' or a blow on the 'Hash Horn' should be given so the 'Knitting Circle' at the back can tell where the trail is. Note that arrows after a closed check may be called differently - see 'Closed Check' below.

On Trail Flour Blob 

A flour blob every so often to denote that you are currently 'On Trail'. Flour is normally preferred on open countryside and grass. A shout of 'On On' or a blow on the 'Hash Horn' should be given so the 'Knitting Circle' at the back can tell where the trail is. Note that flour blobs after a closed check may be called differently - see 'Closed Check' below.

Open Check 

An open check means that you need to look around and find which way the trail leads next.  It could be in any direction. So when you see this one, choose a direction that looks plausible to you and start looking for trail marks. As soon as you find one blob of flour or an arrow, you shout 'On One!' then you keep going on to look for a follow-up mark----when you see it, you shout 'On-Two!'  After that, you need to continue on to find a third mark -either a flour blob or Hash arrow that shows you are on true trail (and when you find it, you shout 'ON-ON!) or if you don't find it, you will see an FT 'false trail' mark that shows you that you have been following a false trail (you shout 'false trail' and need to go back to the check point. 

One Hasher should stay at the check whilst possible trails are being explored by others. As soon as 'On On' is heard, that Hasher should kick out a mark in the check to denote the direction those following should take. This allows those runners who are further back to follow true trail without having to redo the whole checking process themselves each time.

If you are checking and go more than 100 meters without finding any marks it means you are not on trail and need to go back to the check and try again. If you have seen one mark and see nothing after that -go back. If you see two marks and nothing after that, go back. There need to be three On Trail marks in a row for you to be sure you are on True Trail (ON-ON!)

Closed Check 

The closed check is typically placed at visible junctions. From here, the aim is to find where the trail goes next - it will be in the direction of one of the arrows (there may be more than two!). You need to find three blobs of flour or arrows or other Hash marks before you can be sure that you're On Trail. The blobs may be as much as 100m apart. As the blobs/marks are discovered, a shout of 'On One', 'On Two' and eventually 'On On' should be relayed back to the check to keep everyone informed. False trails may have up to two blobs of flour/hash marks to mislead and may be terminated with a False Trail mark.  Once the trail has been found ('On On' from someone checking), the redundant arrows should be scrubbed out from the circle check mark to denote the direction of the trail for those following.
The key to good checking is vocal communication both ways. Those gathered at the check whilst others are checking will be keen to know of progress. A shout of  'Are you?' should elicit the response of 'Checking' from those checking out the trail. It may be worth sending another hound up to relay messages back from the front runners who are checking. At a Closed Check, the count of flour blobs should be relayed back as they are discovered - 'On One', On Two', followed by 'False Trail' or 'On On'. 
If you hear 'On On', that's the direction to go. If you hear 'False Trail' it isn't! A shout of 'On Back' is only given by an attendant Hare who can see that everyone is going ridiculously 'Off Trail' - no one else should use this call as it will confuse the hell out of everyone if heard too often.

False Trail 

This as far as you go. You need to go back to the last check mark and either check another possible trail or await the response of the other front runners that are checking. This is used if the Hare believes you might stumble across another unrelated part of the trail or be in danger of getting ridiculously 'Off Trail'.

Check Back 

You've gone too far but if you look carefully on the way back to the last check, you will see the trail off to the side somewhere!

Loop Back 

As soon as you hit this mark, immediately go back as far as the last runner, loop round him and head back to this mark. If the last runner has still not arrived, go back as far as the last runner, loop round him and head back to this mark. Everyone should continue to do this until everyone has reached the mark. Once everyone is together, carry on in the original direction you were going.

Hash Halt 

You should wait here until the last runner arrives. A Hash Halt is used to bring the pack together. Once together, set off on trail again. If there happens to be Beer here then it's the Beer Stop. Enjoy your refreshment and then off you go. This mark could also be contained within an open or closed check, so after your 'Hash Halt', you may have some checking to do!

Fun Check 

A Hare might fill in a check cirlce with a smiley face just for fun.  If it's in a circle, then you're at a check - get busy!