product versus inventory qty

If I buy bacon by the pound and sell my product by the ounce, how do I set this up?
Is there documentation with this type of detail as I am pretty confused by product versus inventory.
I was asked to write a screen that allows a user to adjust inventory quantity.
I based a custom app on physical inventory variance where I put name and qty on hand and  allow a variance.
It works and I thought life was good until I got a second item for that product now I get two lines.
Our application for ofbiz to use it for inventory for a point of sale app we are developing.
My boss wants the screens as simple as possible. I have seen much doc on developing apps and have a bit of success on our project, but I also need to understand ofbiz as a user how to set up products and suppliers and see the inventory get in (create product, relate to supplier, po, receive). Our POS sells the product and in theory creates the product. Ability to adjust inventory and get reports. I have got inventory into ofbiz to the point I could adjust the variance, but am a bit fuzzy on it especially on how the item quantity relates to the product quantity (bacon example). Any help is much appreciated.

Doing searches in this list I believe I understand some what better a answer.
If I understand what I read there is a unit of measure for a product and a unit of measure for a supplier related inventory item.
So my bacon on the
supplier screen gets
qty included 1
qtyuomid pound
piecesincluded 1
on my product screen
qty included 1
qtyuomid ounce
piecesincluded 4

Recieving uses pound qty and physical adjustments use pound.
Sound correct? I have not tried it yet not sure where I get the Unit of measure ID from as it is not a drop down?
I appreciate help from folks I asked about this like the folks at ANT(Hans Bakker) and Ruth Hoffman.
Ultimately this list has been the most help.

I tired this and it still take a 1 for one even when one is ounces and one is pounds?
I can see the conversion table, what actually uses the conversions.
I am still working on this, will update if I get a decent answer.
I guess you folks know the acronyms better than me, but I have seen post about doing SEC, WHich I am not 100% sure what that is. I am guessing it involves hitting a custom order code where the bacon can be removed by the ounce when purchased. The whole thing is a bit of a puzzle, as to how to do the conversion and when. Obviously the purchase is in the vendor qty (pounds), but once it is moved into the kitchen, does it get stored in pounds or do they spit it up, So if they are taking inventory in the kitchen is it in ounces, so it would also hit custom code and convert. If they stick some in the freezer does it stay in original packaging and get counted in pounds. Lots to figure out and make sure the screens I provide meet the need. I still have not seen a complete overview of entering inventory most examples touch on the screens but do not get into the detail explanation of what each field does and how to use it. I guess you just have to look at several and try to piece it together. I am not sure if the virtual inventory or doing a build process  to say manufacturer the bacon by the ounce (since I need to sell it by the ounce) could be applied. I look into that process as I have not tried to do either of those.

Well after looking at the various posts etc, I think I have something I can work that does not require any custom code. Using MRP to build my product. This gives some advantages too. For example the Bcon by the pound can be counted by the pound and the bacon by the ounce can be counted by the ounce. They are two different products in ofbiz.

What I did was read a document out there called Mfg_5StepsV3final.pdf in google Getting Started
With Apache OFBiz Manufacturing & MRP In 5 Easy Steps.
While this did not actually let me know about quantity, ti did go into pretty excellent detail on how to set up raw materials, finished goods, and the various steps. Briefly (I recommend getting the doc if you plan on trying it, but I did not see the quick receive of P.O. it mentioned, other than that it was spot on).
1. Add the raw materials, this is under catalog-> product. be sure and select raw material when adding. Once added pick the facility tab to set min stock and re-order qty. Associate with a supplier using the supplier tab.
2. Add finished good product what you are building (in my case bacon by the ounce)
3. Set up BOM using manufacturer manager create BOM. Be sure to use manufacturing BOM add items product id is the finished goods, while the product id to is the various raw materials.
NOTE! This is where I did the math to get my bacon by the ounce. My quantity was .25 because ny finished good is 4 ounces and my raw material is one pound so if I multiply by .25 I get the appropriate amount of bacon used from raw materials.
4. Add routing Task (be sure to select manufacturing) mine was like divide package.
5. Add Route edit routing task assoc and add the tasks you did in 4, edit routing product link (select the finished good product to associate the need for the finished good with the tasks.
6. MRP run MRP this looks at the requirements you put, for example if you said you need 10 4 ounce finished bacon it will display a log saying you need 20 and that it takes 2.5 of raw bacon by the pound. It also sets up requirements for order manager.
7. Order manager view requirements This gets a bit complex. The requirements show up as internal (for the 10 4 ounce) and product requirement which is 3.5 pound of raw material (I had set themin qty on hand to 1, so it is wanting 2.5 for the internal need, and 1 for stock. Use Order manager, requirements, approve requirements tab. Select internal requirement and submit to get the work stuff going in manufacturing. Now do raw materials, use order manager, requirements, approve requirements and select the raw materials and approve. Use approve requirements by supplier click prepare order, use purchase order quick entry.
This is where I had to pick a different path than the author. If I had the option he wanted which was quick relieve po I would have selected it, but I did not get that option. I just created the PO. I the had to receive the PO manually. I have to do it again to figure it out for sure, but I believe I did a receive shipment, but I was able to select the P.O. and have it show up in physical inventory after that.  So now I can sell the finished good 4 ounces of bacon, and buy 1 pound. I did see where there was a request in the system to add this functionality to the purchasing, functionality, said it was like 120 hour project. I think the MRP method will work great for us as it allows taking inventory in both sizes.
Thank you to everyone who has helped me on this.

Oh well I just tried to do this process and found in the step that produces the finished good. production run in job shop.
1.confirm
2.quick run all tasks.
3. production run declare and produce : This is blowing up with a invalid format for quantity field.numberFormatException.

Any ideas what needs to be changed? Does it only work with whole numbers?
In which case I am back to square one.

Ran through the process with whole numbers got same error.
I filled in the lot number and seemed to fix it. Going to try with decimals again.

I did it with the onces versu pounds and it worked fine.
Was not the lot number was the stock in field which is what was produced.
This needs a number or it errors with the java number format, be nice if it gave a better error, so the use know what to fix.

My initial impression of ofbiz is so much work has been put and it is a great tool.
There still is much work to be done.

For us I will have to wrap all pars we use, so I will have to ensure good user interface communication.
Maybe that's why its sort of undone in places in regards to detailed help and interface communication.

I will see what I can do to help with documentation as I learn more about the product.