The oxy_indexof() function is used to define searches.
The oxy_indexof() function has two signatures:
Returns the index within text string of the first occurrence of the toFind substring.
Returns the index within text string of the first occurrence of the toFind substring. The search starts from fromOffset index.
oxy_indexof('abcd', 'bc') returns 1.
oxy_indexof('abcdbc', 'bc', 2) returns 4.
image[longdesc]{
content: oxy_substring(attr(longdesc), 0, oxy_indexof(attr(longdesc), "Appendix"));
}