It means "weight for weight", and refers to the adjustments you have to make when substituting ingredients. You haven't given us the ingredients being substituted.
The percentages are baker's percentages, where the amount of each ingredient is specified as a percentage of the total weight of all ingredients. The purpose of writing professional recipes in this way is to make the recipes easily scalable.
For an example of its use, see the table at the end of this webpage, which tells you how you have to adjust the ingredients of a cookie recipe when using artificial butter flavor.
If you need more help, you'll have to give us a longer extract, telling us what ingredients are being substituted.
Baker's percentages are different from the term "w/w" used outside baking, in more general terms, but not all w/w in bakibg recipes uses baker's percentages..
The first link explains them:
For example, in a recipe that calls for 10 pounds of flour and 5 pounds of water, the corresponding baker's percentages are 100% for the flour and 50% for the water. Because these percentages are stated with respect to the mass of flour rather than with respect to the mass of all ingredients, the total sum of these percentages always exceeds 100%.
Outside baking, something that is 5% w/w is a component that is 5% of the total weight of all the components.
In the second of those examples (second link) it was X% w/w of the total dough weight. That is what your context specifies "% w/w of dough weight"
IngredientsControlUsing butter and vergetable shorteningUsing only vegetable shortening
Quantity (% w/w)
Plain Flour 43
Vegetable Shortening 14
Castor Sugar 21
Baking Soda 0.20
Iodized salt 0.20
Butter Flavour 0.10 TOTAL 100