I have been breaking up my conditionals this way (to learn why read this post and this post)
The following two examples will throw a syntax error, unexpected T_ENDIF
{if things != "this_condition"}{if things != "another_condition"}
{exp:channel:entries}
{content}
{/exp:channel:entries}
{/if}{/if}{if things != "this_condition"}
{content}
{/if}{if things != "another_condition"}
{content}
{/if}This can be corrected by adding spaces between conditionals. Per these examples:
{if things != "this_condition"} {if things != "another_condition"}
{exp:channel:entries}
{content}
{/exp:channel:entries}
{/if} {/if}{if things != "this_condition"}
{content}
{/if} {if things != "another_condition"}
{content}
{/if}