1. Select from the source text the list of words $s = \langle s_1, s_2, \dots, s_N \rangle$ belonging to the annotated idiom.
2. For each word $s_i$, obtain its word translations in the target language using a bilingual dictionary and add them to a blocklist b_i = langle t_1, t_2, dots, t_M rangle and create a candidate list of blocklists B_s = langle b_1, b_2, dots, b_N rangle.
3. For each word in the reference (R), search if it occurs in any of the blocklists $b_i$. If so, remove the corresponding blocklist $b_i$ from $B_s$.
4. Check if the hypothesis contains any blocklisted words. If so, mark this hypothesis as having a literal translation error.

The final score is the percentage of translations that trigger the blocklist. Since LiTER requires source-side annotations, test data with idioms on the source side are collected, and the spans where they occur are annotated.