Valid Paypal Buttons
So if you've attempted to make a PayPal button based on the data from PayPal you have something like this.
https://www.paypal.com/xclick/business=email%40yourdomain.com
&item_name=Widget&item_number=001&
amount=15.00&no_note=1&currency_code=USD
Now if you attempted to validate this for XHTML 1.0 you'd get this message:
Line ##, column 71: cannot generate system identifier for general entity "item_name"
Line ##, column 80: reference not terminated by REFC delimiter
Line ##, column 80: reference to external entity in attribute value
Line ##, column 88: cannot generate system identifier for general entity "item_number"
Line ##, column 99: reference not terminated by REFC delimiter
Line ##, column 99: reference to external entity in attribute value
Line ##, column 104: cannot generate system identifier for general entity "amount"
Line ##, column 110: reference not terminated by REFC delimiter
Line ##, column 110: reference to external entity in attribute value
Line ##, column 117: cannot generate system identifier for general entity "no_note"
Line ##, column 124: reference not terminated by REFC delimiter
Line ##, column 124: reference to external entity in attribute value
Line ##, column 127: cannot generate system identifier for general entity "currency_code"
Line ##, column 140: reference not terminated by REFC delimiter
Line ##, column 140: reference to external entity in attribute value
So, what's the solution?
A very simple one here:
Simply change all the & symbols to "&" like this:
https://www.paypal.com/xclick/business=email%40yourdomain.com
&item_name=Widget&item_number=001&
amount=15.00&no_note=1&currency_code=USD
Now, when you try to validate you code you'll get this(as long as you remember to reference the correct doctype)
This Page Is Valid XHTML 1.0 Transitional!