The oxy_lastindexof() Function

The oxy_lastindexof() function is used to define last occurrence searches.

The oxy_lastindexof() function has two signatures:

oxy_lastindexof('abcdbc', 'bc') returns 4.

oxy_lastindexof('abcdbccdbc', 'bc', 2) returns 1.

If we want to display only part of an attribute's value, the part which comes before an Appendix string:
image[longdesc]{
 content: oxy_substring(attr(longdesc), 0, oxy_lastindexof(attr(longdesc), "Appendix"));
}