Can multiple different HTML elements have the same ID if they're different elements?

Question

Can multiple HTML elements have the same ID if they\'re of different element types? Is a scenario like this valid? Eg:

div#foo
span#foo
a#foo

Answer 1

Well, using the HTML validator at w3.org, specific to HTML5, IDs must be unique

Consider the following...

 

    
        
         
    
    
        
Barry
        
was
        
here
    

the validator responds with ...

Line 9, Column 14: Duplicate ID x.      
was
Warning Line 8, Column 14: The first occurrence of ID x was here.       
Barry
Error Line 10, Column 14: Duplicate ID x.       
here
Warning Line 8, Column 14: The first occurrence of ID x was here.       
Barry

... but the OP specifically stated - what about different element types. So consider the following HTML...

 

    
        
         
    
    
        
barry
            was here
        
    

... the result from the validator is...

Line 9, Column 16: Duplicate ID x.          was here
Warning Line 8, Column 14: The first occurrence of ID x was here.       
barry

Conclusion:

In either case (same element type, or different element type), if the id is used more than once it is not considered valid HTML5.