Question: In what ways may cake flour be substituted in a recipe?
About the article "Cake", section "Cake flour".

Candidate passages:
Pound cake refers to a type of cake traditionally made with a pound of each of four ingredients: flour, butter, eggs, and sugar.
The traditional recipe makes a cake much larger than most families can consume, and so the quantity is often changed to suit the size of the cake that is desired.
As long as the ratio is preserved, the resulting cake will be identical to that using the traditional recipe.
Hence, any cake made with a 1:1:1:1 ratio of flour, butter, eggs, and sugar is also called a pound cake.
Pound cakes are generally baked in either a loaf pan or a Bundt mold, and served either dusted with powdered sugar, lightly glazed, or sometimes with a coat of icing. 
Some commonly used ingredients in depression cake: white sugar, brown sugar, molasses,  corn syrup, strong coffee, water, or apple juice, shortening, dark raisins or diced pitted prunes, apple, unsifted all-purpose flour, rye flour, salt baking soda, baking powder, cinnamon, allspice, clove, nutmeg, chopped walnuts, almonds, or pecans.
Pears were sometimes substituted for apples.
An example for a depression cake recipe is as follows: Preheat oven to 350°F.
Grease a 13 by 9 in baking pan.
In a large saucepan, combine 1 cup white sugar, 2 cups firmly packed brown sugar, 2 cups water, 1 cup shortening, 4 cups seedless raisins, 1 tsp cinnamon, 1 tsp nutmeg, 1/2 tsp cloves, and 2 tsp salt.
Boil together for 3 minutes, then cool.
Sift together 4 cups flour, 2 1/2 tsp baking powder, 2 tsp baking soda.
Add to saucepan, along with 2 cups chopped nuts (optional.)
Mix well and pour into baking pan.
Bake for 45 minutes.
Remove from oven.
Let cool for 10 minutes, then turn onto a cake plate.
When thoroughly cool, sprinkle with a little powdered sugar or mix lemon juice and grated lemon rind into powdered sugar for frosting.
This is one example of a depression cake recipe.
Other variations may include corn syrup, molasses, brown sugar, and various fruits.
In some instances, bakers would leave the cake unfrosted or sprinkle the top with powdered sugar in lieu of icing.
The interchangeability of ingredients makes the recipe for depression cake extremely versatile. 
Sponge cake is a cake based on flour (usually wheat flour), sugar, and eggs, sometimes leavened with baking powder which has a firm, yet well aerated structure, similar to a sea sponge.
A sponge cake may be produced by the batter method or the foam method.
Cake made using the batter method is known as a butter or pound cake in the U.S., while in the U.K. it is known as Madeira cake or Victoria sponge cake.
A cake made using the foam method is known as a sponge cake or, in the U.K., also as whisked sponge.
These forms of cake are common in Europe, especially in French patisserie.
The sponge cake is thought to be one of the first of the non-yeasted cakes, and the earliest attested sponge cake recipe in English is found in the 1615 book of English poet and author Gervase Markham, "The English Huswife, Containing the Inward and Outward Virtues Which Ought to Be in a Complete Woman".
Though it does not appear in Hannah Glasse's "The Art of Cookery" in the late 18th century, it is found in Lydia Maria Child's "The American Frugal Housewife", indicating that sponge cakes had been established in Grenada in the Caribbean, by the early 19th century.
Variations on the theme of a cake lifted, partially or wholly, by trapped air in the batter exist in most places where European patisserie has spread, including the French Génoise, the Portuguese pão-de-ló, the Anglo-Jewish "plava", and the possibly ancestral Italian "pan di Spagna" ("Spanish bread").
Derivatives of the basic sponge cake idea include the American chiffon cake and the Latin American Tres leches cake. 
A traditional American pound cake would contain one pound each of flour, butter, eggs, and sugar.
This recipe is quite popular in the cuisine of the Southern United States. 
Potato bread is a form of bread in which potato replaces a portion of the regular wheat flour.
It is cooked in a variety of ways, including baking it on a hot griddle or pan, or in an oven.
It may be leavened or unleavened, and may have a variety of other ingredients baked into it.
The ratio of potato to wheat flour varies significantly from recipe to recipe, with some recipes having a majority of potato, and others having a majority of wheat flour.
Some recipes call for mashed potatoes, with others calling for dehydrated potato flakes.
It is available as a commercial product in many countries, with similar variations in ingredients, cooking method, and other variables.