Schematic showing the CE formation channel for TŻOs, based on Fig. 1 of Vigna-Gómez et al. (2020), Vigna-Gómez & Rebagliato (2020). The chronology and the nomenclature is the following. 1. Zero-age main sequence (ZAMS); 2. Roche lobe overflow (RLOF); 3. Post-RLOF, or envelope detachment; 4. Supernova (SN) of the primary; 5. Neutron star (NS) forms from the SN explosion; 6. Common envelope evolution (CE evolution); 7. Post-CE evolution, which can lead to either the ejection of the envelope, forming a stripped star + NS, or the formation of a TŻO from the merger of the NS and the stellar core; 8. RLOF of the stripped binary, further stripping the companion star; 9. Ultra-stripped SN of the companion star; and 10. NS binary. The solid arrow from step 6 indicates the CE formation channel for TŻOs and the dashed arrow from step 8 shows the alternative channel to a TŻO with a HeMS donor star.