On hand inventory – what does it all mean??
One of the most important parts of an ERP for a manufacturing or distribution company is knowing what material you have available, what you need to make, and where it all is. When you open up on the on-hand form in Dynamics AX, you are a greeted with a plethora of similar sounding field names. Every time I open this form, I have to spend 5 minutes thinking about what each of the terms mean. I’ve put together a brief cheat sheet that I use to remember which each field means, and I figured I’d share it. 
Physical inventory
This field represents the physical quantity you should be able to find if you went out and tried to do an inventory count. (Financially updated quantity) + (Quantity received but not yet invoiced) – (Quantity issued but not yet invoiced) + Registered – Picked
Physical reserved
How many of the physical inventory is reserved.
Available physical
How many of the physical inventory is actually available for use and not reserved. (Physical inventory) – (Physical reserved)
Ordered in total
The amount of material expected to come in. Expected receipts. An example would be purchase orders that have not been received. Ordered + (Arrived on arrival journal but not yet received)
On order
The amount of material expected to go out. Expected issues. An example would be an open sales order that has not yet been shipped.
Ordered reserved
The amount of material that is expected to come in, but is already reserved. Either caused by purchase orders (if you have the reserve ordered items parameter enabled) that are already reserved or by quarantine orders.
Total available
How much inventory will eventually be available. Takes the available physical (which already removes reserved amounts) and adds expected receipts and subtracts expected issues. (Available physical) + Ordered + Arrived – (Ordered reserved) – (On order)