Recipe DTD:

<!ELEMENT RECIPE (TITLE, INFO, INGREDIENTLIST, STEPLIST)>
<!ATTLIST RECIPE ID CDATA #REQUIRED>

<!ELEMENT TITLE (#PCDATA)>

<!ELEMENT INFO (COUNTRY, YIELD, CALORIES)>
<!ELEMENT COUNTRY (#PCDATA)>
<!ELEMENT YIELD (#PCDATA)>
<!ELEMENT CALORIES (#PCDATA)>

<!ELEMENT INGREDIENTLIST (INGREDIENT*)>
<!ELEMENT INGREDIENT (QUANTITY, PRODUCT)>
<!ELEMENT QUANTITY (#PCDATA)>
<!ELEMENT PRODUCT (#PCDATA)>
<!ATTLIST PRODUCT    
                             MEAT (yes | no) #REQUIRED
                             AISLE (baking | dairy | spices | fruitnuts) #REQUIRED>

<!ELEMENT STEPLIST (STEP*)>
<!ELEMENT STEP (#PCDATA)>