Validation of the HTML codes

[SWSUSA]

Hi! Help fix the HTML code and make the site fully valid.

When checking the site services validator.w3.org get 5 errors and 8 warnings.

Validation Output: 5 Errors

Line 213, Column 103: cannot generate system identifier for general entity "contenttype"
?94921a781d94dab257e5334&do=getnew&contenttype =vBForum_Post">Новые сообщени?
✉
An entity reference was found in the document, but there is no reference by that name defined. Often this is caused by misspelling the reference name, unencoded ampersands, or by leaving off the trailing semicolon (. The most common cause of this error is unencoded ampersands in URLs as described by the WDG in "Ampersands in URLs".

Entity references start with an ampersand (&) and end with a semicolon (. If you want to use a literal ampersand in your document you must encode it as "&" (even inside URLs!). Be careful to end entity references with a semicolon or your entity reference may get interpreted in connection with the following text. Also keep in mind that named entity references are case-sensitive; &Aelig; and æ are different characters.

If this error appears in some markup generated by PHP's session handling code, this article has explanations and solutions to your problem.

Note that in most documents, errors related to entity references will trigger up to 5 separate messages from the Validator. Usually these will all disappear when the original problem is fixed.

Line 213, Column 103: general entity "contenttype" not defined and no default entity
?94921a781d94dab257e5334&do=getnew&contenttype =vBForum_Post">Новые сообщени?
✉
This is usually a cascading error caused by a an undefined entity reference or use of an unencoded ampersand (&) in an URL or body text. See the previous message for further details.

Line 213, Column 114: reference not terminated by REFC delimiter
?d94dab257e5334&amp;do=getnew&contenttype=vBForum_ Post">Новые сообщения</a></li>
✉
If you meant to include an entity that starts with "&", then you should terminate it with ";". Another reason for this error message is that you inadvertently created an entity by failing to escape an "&" character just before this text.

Line 213, Column 114: reference to external entity in attribute value
?d94dab257e5334&amp;do=getnew&contenttype=vBForum_ Post">Новые сообщения</a></li>
✉
This is generally the sign of an ampersand that was not properly escaped for inclusion in an attribute, in a href for example. You will need to escape all instances of '&' into '&amp;'.

Line 213, Column 114: reference to entity "contenttype" for which no system identifier could be generated
?d94dab257e5334&amp;do=getnew&contenttype=vBForum_ Post">Новые сообщения</a></li>
✉
This is usually a cascading error caused by a an undefined entity reference or use of an unencoded ampersand (&) in an URL or body text. See the previous message for further details.

Line 213, Column 102: entity was defined here
?a94921a781d94dab257e5334&amp;do=getnew&contenttyp e=vBForum_Post">Новые сообщен?
Line 246, Column 108: cannot generate system identifier for general entity "markreadhash"
?921a781d94dab257e5334&amp;do=markread&markreadhas h=guest">Все разделы прочитан?
✉
An entity reference was found in the document, but there is no reference by that name defined. Often this is caused by misspelling the reference name, unencoded ampersands, or by leaving off the trailing semicolon (. The most common cause of this error is unencoded ampersands in URLs as described by the WDG in "Ampersands in URLs".

Entity references start with an ampersand (&) and end with a semicolon (. If you want to use a literal ampersand in your document you must encode it as "&amp;" (even inside URLs!). Be careful to end entity references with a semicolon or your entity reference may get interpreted in connection with the following text. Also keep in mind that named entity references are case-sensitive; &Aelig; and &aelig; are different characters.

If this error appears in some markup generated by PHP's session handling code, this article has explanations and solutions to your problem.

Note that in most documents, errors related to entity references will trigger up to 5 separate messages from the Validator. Usually these will all disappear when the original problem is fixed.

Line 246, Column 108: general entity "markreadhash" not defined and no default entity
?921a781d94dab257e5334&amp;do=markread&markreadhas h=guest">Все разделы прочитан?
✉
This is usually a cascading error caused by a an undefined entity reference or use of an unencoded ampersand (&) in an URL or body text. See the previous message for further details.

Line 246, Column 120: reference not terminated by REFC delimiter
?4dab257e5334&amp;do=markread&markreadhash=guest"> Все разделы прочитаны</a></li>
✉
If you meant to include an entity that starts with "&", then you should terminate it with ";". Another reason for this error message is that you inadvertently created an entity by failing to escape an "&" character just before this text.

Line 246, Column 120: reference to external entity in attribute value
?4dab257e5334&amp;do=markread&markreadhash=guest"> Все разделы прочитаны</a></li>
✉
This is generally the sign of an ampersand that was not properly escaped for inclusion in an attribute, in a href for example. You will need to escape all instances of '&' into '&amp;'.

Line 246, Column 120: reference to entity "markreadhash" for which no system identifier could be generated
?4dab257e5334&amp;do=markread&markreadhash=guest"> Все разделы прочитаны</a></li>
✉
This is usually a cascading error caused by a an undefined entity reference or use of an unencoded ampersand (&) in an URL or body text. See the previous message for further details.

Line 246, Column 107: entity was defined here
?4921a781d94dab257e5334&amp;do=markread&markreadha sh=guest">Все разделы прочита?
Line 258, Column 115: reference not terminated by REFC delimiter
?ab257e5334&amp;do=getdaily&contenttype=vBForum_Po st">Сообщения за день</a></li?
✉
If you meant to include an entity that starts with "&", then you should terminate it with ";". Another reason for this error message is that you inadvertently created an entity by failing to escape an "&" character just before this text.

Line 258, Column 115: reference to external entity in attribute value
?ab257e5334&amp;do=getdaily&contenttype=vBForum_Po st">Сообщения за день</a></li?
✉
This is generally the sign of an ampersand that was not properly escaped for inclusion in an attribute, in a href for example. You will need to escape all instances of '&' into '&amp;'.

Line 258, Column 115: reference to entity "contenttype" for which no system identifier could be generated
?ab257e5334&amp;do=getdaily&contenttype=vBForum_Po st">Сообщения за день</a></li?
✉
This is usually a cascading error caused by a an undefined entity reference or use of an unencoded ampersand (&) in an URL or body text. See the previous message for further details.

Line 213, Column 102: entity was defined here
?a94921a781d94dab257e5334&amp;do=getnew&contenttyp e=vBForum_Post">Новые сообщен?


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I have simple, I want to fix, but don't know how. Surely it is not difficult for a person, who are versed in this.