A question for parsing experts: How to recognize that '<' denotes the beginning of a start tag?

Hi Folks,

Suppose you are scanning an XML document or HTML document from the first character to the last character.

In the scanning process, you encounter a less than ( '<' ) symbol.

You must determine if it denotes the beginning of a start tag.

What checks must be made to make this determination?

I think these are the checks:

Let c = the character currently being examined.
Let nextchar = the character following c

if c == '<' and nextchar != '/' and nexchar != '!' and nextchar != '?' then we are at the beginning of a start tag

Do you agree? Am I missing any checks?

/Roger