+ tidy autoconf.html
line 1 column 1 - Warning: missing <!DOCTYPE> declaration
line 15 column 3 - Warning: missing <li>
line 21 column 3 - Warning: missing <li>
line 28 column 1 - Warning: missing </a> before <h2>
line 29 column 5 - Warning: inserting implicit <a>
line 32 column 1 - Warning: inserting implicit <a>
line 42 column 1 - Warning: inserting implicit <a>
line 57 column 1 - Warning: inserting implicit <a>
line 63 column 1 - Warning: inserting implicit <a>
line 63 column 1 - Warning: missing </a> before <ul>
line 107 column 1 - Warning: inserting implicit <p>
line 142 column 1 - Warning: inserting implicit <p>
line 145 column 1 - Warning: missing </a> before <h2>
line 146 column 5 - Warning: inserting implicit <a>
line 149 column 1 - Warning: inserting implicit <a>
line 149 column 1 - Warning: missing </a> before <a>
line 158 column 1 - Warning: missing <li>
line 158 column 1 - Warning: missing </a> before <li>
line 166 column 1 - Warning: missing <li>
line 166 column 1 - Warning: missing </a> before <li>
line 175 column 1 - Warning: missing <li>
line 207 column 1 - Warning: inserting implicit <p>
line 209 column 1 - Warning: missing </a> before <li>
line 217 column 1 - Warning: missing <li>
line 227 column 1 - Warning: inserting implicit <p>
line 232 column 1 - Warning: missing </a> before <h2>
line 233 column 5 - Warning: inserting implicit <a>
line 236 column 1 - Warning: inserting implicit <a>
line 236 column 1 - Warning: missing </a> before <a>
line 242 column 1 - Warning: missing <li>
line 242 column 1 - Warning: missing </a> before <li>
line 248 column 1 - Warning: inserting implicit <p>
line 251 column 1 - Warning: missing </a> before <h2>
line 252 column 5 - Warning: inserting implicit <a>
line 255 column 1 - Warning: inserting implicit <a>
line 255 column 1 - Warning: missing </a> before <ul>
line 271 column 1 - Warning: inserting implicit <p>
line 32 column 1 - Warning: <a> anchor "basic" already defined
line 38 column 1 - Warning: <a> anchor "basic" already defined
line 42 column 1 - Warning: <a> anchor "basic" already defined
line 53 column 1 - Warning: <a> anchor "basic" already defined
line 57 column 1 - Warning: <a> anchor "basic" already defined
line 63 column 1 - Warning: <a> anchor "basic" already defined
line 149 column 1 - Warning: <a> anchor "driver" already defined
line 236 column 1 - Warning: <a> anchor "library" already defined
line 255 column 1 - Warning: <a> anchor "demos" already defined
line 107 column 1 - Warning: trimming empty <p>
line 142 column 1 - Warning: trimming empty <p>
line 175 column 1 - Warning: trimming empty <p>
line 207 column 1 - Warning: trimming empty <p>
line 217 column 1 - Warning: trimming empty <p>
line 227 column 1 - Warning: trimming empty <p>
line 248 column 1 - Warning: trimming empty <p>
line 271 column 1 - Warning: trimming empty <p>
Info: Document content looks like HTML 4.01 Transitional
Info: No system identifier in emitted doctype
54 warnings, 0 errors were found!

Note: HTML tidy reports these as warnings because it things it can deal with them.  They are errors and they cannot be automatically fixed because the existing markup is semantically flawed anyway.