Think of a Commercial Package Policy (CPP) as a set of building blocks. Instead of one preset policy for every business, the insurer assembles standard pieces that fit this insured's exposures. That is the "modular" concept, and it is why two CPPs can look quite different.
The building blocks:
Common Policy Declarations
One or more coverage parts, each with its own declarations and coverage form (plus other forms where needed, such as a causes of loss form for property)
Two modules appear in every CPP, whatever coverage is bought: the Common Policy Declarations and the Common Policy Conditions. All the coverage parts share them. A property form or a liability form appears only if that coverage is purchased.
The Common Policy Declarations carry what applies to the whole policy: the named insured and mailing address, the policy period, the coverage parts included and the premium. Line-specific details, such as a building limit or a deductible, go in the declarations of the coverage part, because they differ from one line to another.