The document below is based on EPM SP16 Patch 1. The documentation is sometimes confusing and I want to show some step by step examples of protecting sheet.
Simple scenario:
We create some simple EPM report on the worksheet without changing "Locked" property of cells (all cells are Locked by default for new Excel sheet) and without protection. This report will be "static", we inserted 2 columns between column axis members. We also set "Use as Input Form" property to make it input schedule.
For all cells on this sheet the Excel Locked property is set:
EPM User settings are:
Not selected Protect Only Sheets Containing EPM Reports - All sheets will be protected. In our case it doesn't matter - we have only one sheet containing EPM report.
What happens if we switch on Offline Mode?
The red area will be available for input, all other cells will be locked:
If we switch off Offline Mode and inspect the Excel cells property we can see that "Locked" property was switched off for the red area!
It means that Offline Mode uses simple algorithm to define input area - rectangle:
First Data column to First Data Column + number of Data Columns
First Data Row to First Data Row + number of Data Rows
Definitely some bug!
If you change the locked property of any cell inside or outside red area and enable/disable Offline Mode all changes in the locked cell property will be removed, only red area will be unlocked!
This simple approach is not very useful because in real life you need to precisely control which cell have to be locked or available for input. This is especially critical when Keep Formula on Data option is enabled and the input is done using Excel links to some calculations.
Also, the Offline Mode protection is done by some unknown password and there is no way to correct the template after saving it in Offline Mode.
Scenario with Sheet Protection:
Using the same sample template let's change the Locked property of blue areas to On and for red area - to Off.
Then, lets protect sheet using Options -> Sheet Options -> Protection:
And then enable Offline Mode!
The result: red areas will be available for input and blue areas will be locked.
This way (combination of Protection and Offline mode) we can control the Locked property of any cell. The Offline version will be secured with unknown password, but the Protection password will be restored when we switch from Offline to Online.
B.R. Vadim