Enter Form
Click on screen capture to view at full resolutionObviously an Inventory with no data is worthless, so the initial step working with the Inventory workbook will be to enter data.  This is accomplished by clicking on the "Enter" button on the CommandBar.
The Enter button displays the Inventory Enter Form over the workbook.  I find it most convenient to position the form just below the layout drawing so I can refer to the locker IDs while entering data.
Click on screen capture to view at full resolutionIn the screen on the left I have started to enter a new item into the inventory.  You can fill in the form fields in any order you like.  Nothing happens until you click on the "Enter this Item" button at the bottom of the form.
I have started by selecting the "Hardware" category from the drop down list.
Click on screen capture to view at full resolutionNext I have selected a subcategory of "Fasteners".  How you categorize an item is strictly up to you.  It is not necessary to categorize any or all of the items in the inventory, but it is a useful way to keep the inventory organized.
Notice that the button in the lower left corner of the form is blank.  This is the "Enter Item" button, but it does not become active until at least one character has been entered in the Item Description field at the top of the form.

Click on screen capture to view at full resolution
The first location parameter is the cabin.  Specifying a cabin serves two purposes

1. It limits the number of lockers you have to consider in the next parameter; and
2.  Not everything goes in a locker.  Some things are mounted on bulkheads or hung under deck.

In this case the fasteners are located in the Forward cabin.

You must enter a Cabin location, but you don't need to enter a Locker for the item.  However, what is the purpose of an inventory if it doesn't tell you where things are located?  You already knew you had a widget onboard, the problem is you can't remember the very logical place you stored it.
So a locker is pretty important and probably shouldn't be omitted unless, of course, the item does not reside in  a locker.

Click on screen capture to view at full resolutionThere are two ways to identify the locker where the item is located.  One is with the Locker ID list shown in the screen capture on the left.  The IDs in this list correspond to the IDs in the Layout diagram.  This list in conjunction with the diagram is usually the quickest and most reliable way to specify the locker.
In this case I've selected Locker "68".
Click on screen capture to view at full resolutionThe other way is to use the locker description, but it is easy to confuse lockers that have very similar descriptions.
Click on screen capture to view at full resolutionIn this screen I have completed the Enter form.  I have described the item as various machine screws.  I have two toolboxes of machine screws on Sarah so I have set the quantity to 2 and used the "Container" unit.  Although it possible to use this workbook to inventory every screw, bolt and nut on Sarah, that is more detail than I want to manage so I just account for the individual boxes in which I store my fasteners.

Now that I've entered a description of this item, the "Enter Item" button (lower left) is now active.  It is also the default button for the form so I could add this item to the inventory either by clicking on the button or just hitting the "Enter" key.
Click on screen capture to view at full resolutionAfter the fasteners containers have been added to the inventory a status line just above the buttons (red arrow) confirms the update.
Notice that the data entered on the form has not been cleared and the "Enter Item" button has now been changed to "Correct Item" (red rectangle).  If I'd made a mistake in one of the fields or forgot something I can now edit the fields and update the record.
Click on screen capture to view at full resolutionI have decided to add more information to the Item Description field so I clicked on the "Correct Item" button.
Now the button reads "Re-Enter Item" and I can change any of the fields and update the record I just created.
If I had started to modify any of the fields before clicking the "Correct Item" button the form would have assumed I was entering a new record (see below).
Click on screen capture to view at full resolutionI updated the Item Description and hit the Enter key.  The status line (red arrow) now confirms that I have re-entered the record with the new description.
Once again the lower left button is labeled "Correct Item".  If I wanted to make still another change to the record I would click this button or just hit the Enter key one more time.
Click on screen capture to view at full resolution Instead I want to enter my next inventory item.  As soon as I modify the Item Description by changing "Machine screws" to "Self-taping screws", the lower left button becomes "Enter Item".  If wanted to go back and change the previous record I would have to close the Enter form and open the Edit form.
Click on screen capture to view at full resolution I entered the second new item then closed the Enter form and clicked on the tab for the "Inventory" worksheet.  At the bottom of the Inventory are the two Items I have just added (red rectangle).
The Inventory worksheet is just a normal spreadsheet, but with no formulas or calculations - just data.  You can manually enter, edit, sort and delete records from this worksheet without using the workbook forms.  However, the forms will help avoid typographical errors that might result in that widget you finally found and have just entered into the database (but with a typo on the locker ID) to be lost once more.
The screen captures above were taken from version 2.6 and earlier.  With 2.7 I added the capability to enter an expiration date, serial number, and cost of an inventory item.
These new fields can be entered by checking the appropriate box on the right side of the Enter Form as shown in this screen capture.  There is one check box for each of these additional inventory fields.
If you check one or more of these boxes, the Enter Form expands to allow you to enter the additional field as shown in this screen capture.
In this case I've checked the expiration date and serial number boxes and the form has expanded to include text boxes in which the data and number can be inserted.  If I had also checked the Add Item
Cost box, a field for the cost would also appear on the right side of the form.
In the case of the Expiration Date, I can either type a date into the text box, or click on the button to the right of the box and use the date form to enter the date in this field.
Edit Form
Click on screen capture to view at full resolutionClicking on the Edit CommandBar button brings up the Edit Form shown on the left.  There are two parts to the Edit Form.
1. Selection Criteria (Blue Outline).  This where you specify category and location parameters to find the item or items you want to modify.
2.  Edit Data (Green Outline).  This is where the record you want to edit is displayed.  You can change any or all of the fields in this record and click on the "Save Changes" button and the new data will be stored in the database.
Notice that the "Save Changes" button is grayed-out.  This button only becomes enabled, and the active button, when you modify any of the fields of a record in the Edit Section of the form.
Click on screen capture to view at full resolutionZooming in on the Selection section, there are two fields that hold information on any records that meet the selection criteria.  The Item Count field displays how many records have been selected based on the criteria.  Since no selection criteria have been set, no records have been found.
Next to the Item Count is a drop down list of all of the records that have been found.  Select a record off this list to edit its contents.
Click on screen capture to view at full resolutionI've entered a cabin location of "Aft" in the selection criteria and now there are 127 items that are located in the Aft Cabin.  These records are shown in the drop down list.
Presumably the inventory item I want to edit is in this list, but it might take me awhile to find it.  So I probably should refine my selection criteria.
Click on screen capture to view at full resolutionI have refined the criteria to one locker in the Aft Cabin.  Now the drop down list has been reduced to a manageable 4 items.
Click on screen capture to view at full resolution I have selected the "Passport Copy" item from the list (red arrow) and the inventory data on this record is displayed in the Edit Section of the form.
Now that I've selected a record the "Delete This Item" button has become active.  If I wanted to delete this record I would click on this button.
I don't want to delete this record, just modify it.  Because I have not yet made any changes the "Save Changes" button is not active.
Click on screen capture to view at full resolution I have moved the copies of my passport to the locker over my berth (red arrow) and I added the expiration date for the passport of which these are copies.
Now the "Save Changes" button is active and I can update the record with the new data.
Click on screen capture to view at full resolution When I clicked on the "Save Changes" or hit the Enter key the Passport copy record is updated with the new location.  Since I used the location data for my selection criteria and the Passport copies are no longer in that location they do not appear in the selection drop down list (red arrows).
Click on screen capture to view at full resolution I closed the Edit form and clicked on the tab for the "Inventory" worksheet.  The updated record is shown in the red rectangle.
Click on the screen capture to view at full resolutionIf I didn't know the location of the passport copies I could have used the "Documentation/Personal" category/subcategory to find them.
Click on screen capture to view at full resolution Another way to find items in the inventory for editing is to use the key word search. 
In this screen I have entered "glass" as a key word (red rectangle).  Immediately the form shows 8 items (red arrows) with that key word (partial or full) in the Item Description field.
Click on screen capture to view at full resolution I can also use the key word search in conjunction with the other selection criteria (red rectangle) to further reduce the edit list to a single item (red arrows).  Yes, I am at the age where eyeglasses are probably the most important Navigation instruments onboard Sarah.
Each of the selection criteria specified are logical AND conjunctions.  That is the items found and placed in the "Items to Edit" list must meet all of the selection criteria.
You can enter multiple key words separated by commas (",").  The key words are used as a OR logical conjunction.  That is records that contain any of the key words in their descriptions (AND meet the other criteria specified) will be put in the edit list.
Click on screen capture to view at full resolution To illustrate this ANDing and ORing, I added a second key word, "compass", to the key word field. 
Now a second item is placed in the list.  My binoculars, with a bearing compass, are also classified in the Navigation category so they now appear in the edit list in addition to the eyeglasses.
Click on screen capture to view at full resolution Just below the key word field is a check box, "Check to include items in kits".  If this checkbox is clear items that have been added to any of the Critical Kits in the inventory will NOT be placed in the "Items to Edit" list even if they meet all the criteria.
In this screen I have checked this box and two additional fields appear on the form, one in the selection section and one in the edit section.
Click on screen capture to view at full resolution Now when I specify the "Electronics" category the drop down list contains all items, including those in kits, which have been classified in that category.
Click on screen capture to view at full resolution I selected the ACR Epirb from this list and the data from this record are displayed in the Edit Section.  Now the new field, "Reserved for this Kit" shows the Epirb is part of the Abandon Ship kit.  This field is grayed-out and you cannot change this field in the Edit form.  You can only change kit contents in the Kits form.
Click on screen capture to view at full resolution Having checked the "...include items in kits" box I could also use the a kit name as a selection criteria.  In this screen I have selected the "Abandon Ship" kit and the contents of this kit are now in the edit list.
Version 2.7 of the Inventory added fields for an Expiration Date, Serial Number, and an Item Cost.  These fields can be modified in the edit form as shown in this screen capture.  I have selected the inventory record for the Epirb on Sarah.  This item has a serial number, and expiration date (battery) and a cost as shown in the red rectangle at the bottom of the form.  I can modify and of these fields by entering new values in the text boxes.
Or in the case of the Expiration Date I can click on the button next to the text box, which calls up a calendar form that can be used to modifiy the date.