RET uses single-brace delimiters for woodcuts, devices, engravings, rules, borders, ornaments like the leaf, and a grouping image like the multi-line brace. To identify such an image, use the <imag src=""> tag.
RET Description
Code
{3{} opening brace covering 3 lines
{5}} closing brace covering 5 lines
{leaf} leaf
{1rule} single line
{ornament} ornament of whatever kind
{woodcut} woodcut
{device} printer's device
{engraving} engraving