2.1.644 Part 1 Section 220.127.116.11, sheetProtection (Sheet Protection Options)
a. The standard does not specify any restrictions for a dialogsheet parent element.
For a dialogsheet parent element, Office requires that the dialog sheet is protected when the attributes objects and scenarios are true. The dialog sheet should not be protected when the attributes objects and scenarios are false. No other values are allowed. In addition, the sheet attribute is always true and all other attributes are their default value.
b. The standard states that this setting uses a specific Password attribute to store the password hash.
see extended information