Truthy/falsy per JavaScript usual, except empty arrays are falsy
{{> item }} – interpolate item
{{= item }} – interpolate item, escaped
{{> item? }} – if item truthy, interpolate item
{{= item? }} – if item truthy, interpolate item, escaped
{{? item : ... }} – if item truthy, process ...
{{! item : ... }} – if item falsy, process ...
{{? item -: ... }} – if item truthy, process ...(trimmed)
{{! item -: ... }} – if item falsy, process ... (trimmed)
{{* items |item| ... }} – iterate
{{* items -|item| ... }} – iterate (trimmed)
{{? : ... }} – if last ?/!/* item truthy, process ...
{{! : ... }} – if last ?/!/* item falsy, process ...
{{? -: ... }} – if last ?/!/* item truthy, process ... (trimmed)
{{! -: ... }} – if last ?/!/* item falsy, process ... (trimmed)
{{# this is a comment }} – comment (cannot currently contain other braces)
{{{}} – literal open bracket
{{}} – literal close bracket
{-{ ... }} - trim whitespace before
{{ ... }-} - trim whitespace after
{-{ ... }-} - trim whitespace before and after