The oxy_indexof() Function

The oxy_indexof() function is used to define searches.

The oxy_indexof() function has two signatures:

oxy_indexof('abcd', 'bc') returns 1.

oxy_indexof('abcdbc', 'bc', 2) returns 4.

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_indexof(attr(longdesc), "Appendix"));
}