Does 'samadhi-nimitta' mean 'undistractable-lucidity-themes'?

I read the following on the internet: > In MN 44, the four remembrance-establishings (are) > undistractable-lucidity-themes. > > Any topic for satipatthana "mindfulness", can be a topic for samādhi > nimitta, or a subject for jhāna meditation to investigate with > dhamma-vicaya, vitakka and vicāra, upekkha, sati and sampajāno in the > higher jhānas. The nimitta of samādhi can be visual, or conceptual, > and both, just as it can be in guarding the sense doors. > In AN 4.14, samādhi nimitta suggested one develops are the corpse in > various stages. > > Idha, bhikkhave, bhikkhu uppannaṃ bhaddakaṃ samādhinimittaṃ > anurakkhati aṭṭhikasaññaṃ puḷavakasaññaṃ vinīlakasaññaṃ > vicchiddakasaññaṃ uddhumātakasaññaṃ. It’s when a monk preserves a > meditation subject that’s a fine basis of undistractible-lucidity: the > perception of a skeleton, a worm-infested corpse, a livid corpse, a > split open corpse, or a bloated corpse. Does the term 'samādhi nimitta' in MN 44 above really mean '*undistractable-lucidity-themes*'? If so, why is 'samādhi nimitta' translated as '*basis of undistractible-lucidity*' in AN 4.14 above?