You can add internal notes to your Product Costings - create Product Note Tags to help you manage these
Select [+ Add] to create new Product Note Tag
Enter a Note Tag name, add additional as required
You can search for Product Note Tags within the Notes tab of a Product Costing (in the Product Costings module) and use the following report in the Reports module:
'Reports' > 'System Reports' > 'Products' > 'Product' > 'Full Product Notes'