I did find this in the validator.w3.org error docs... the same validator you use.
In fact, unless you have extreme file size requirements it is a very very good idea to always put quote marks around your attribute values. It is never wrong to do so, and very often it is absolutely necessary.
I did find this in the validator.w3.org error docs... the same validator you use.
validator.w3.org/docs/errors.html#...