The format for a predicate is {.predicate-name?} ... {.end}. You can generally spot a predicate by the trailing question mark.

Collection Predicates

These tags are used in collection template files (.list, .item).

Main Image Predicate

{.main-image?}
  <!-- code here -->
{.end}

Tests the presence of a Main Image for a collection or item.

Excerpt Predicate

{.excerpt?}
  <!-- code here -->
{.end}

Tests the presence an excerpt for an item.

Comments Enabled Predicate

{.comments?}
  <!-- code here -->
{.end}

Tests if comments are enabled for a particular item.

Disqus Enabled Predicate

{.disqus?}
  <!-- code here -->
{.end}

Test is Disqus comments have been enabled (only useful in items with comments enabled).

Video Predicate

{.video?}
  <!-- code here -->
{.end}

Tests if an item within a Gallery Collection is a video.

Even Predicate

{.even?}
  <!-- code here -->
{.end}

Tests if an item's index position is even.

Odd Predicate

{.odd?}
  <!-- code here -->
{.end}

Tests if an item's index position is odd.

Equal Predicate

{.equal? arg1 arg2}
  <!-- code here -->
{.end}

Tests if two alpha-numeric arguments are equal. If true, anything between the condition {.equal?} and {.end} will be output. If either of your arguments may contain spaces, use a delimiter other than a space to ensure an accurate return. For example: {.equal?:arg1:arg2}.

Navigation Predicates

These predicates are only used within navigation (.block) files.

Collection Predicate

{.collection?}
  <!-- code here -->
{.end}

Tests if a navigation item is a collection.

External Link Predicate

{.external-link?}
  <!-- code here -->
{.end}

Tests if a navigation item is an external link.

Folder Predicate

{.folder?}
  <!-- code here -->
{.end}

Tests if a navigation item is a folder.