OPEX = SG&A + R&D + Depreciation + Amortization

Depreciation & Amortization represent a Non-Cash Expenses.

In some specific cases a part of R&D or the whole cost of R&D can be captured as:

COGS

or

CAPEX and then amortized over time (see R&D record in P&L).

See also

Business / Business Administration / Financial Management / Financial Accounting / Profit and Loss (P&L)

Expenses typically include:

Materials used in manufacturing and procurement of the Product
Labour used in manufacturing and procurement of the Product, including labour taxes
Liabilities related to manufacturing and procurement of the Product, such as royalty