Olaf mentioned those plants that can't produce anthocian, albino forms. I think that is the most appropriate terminology for these plants. Albino forms can be viride, viridoflava, alboflava, flava, alba etc.Another caveat: if we follow the strict nomenclatura propagated by some eminent botanists within Paphiopedilum (Gruß, Braem), it can NEVER bloom completely alba - as this term in botany is exclusively reserved for plants that blooms without any colour pigmentation, i.e. with completely and all white flowers.
I guess a proper designation for David's and Istvan's flowers would be 'alboflava' (white and yellow). At least if you can't detect any pinkish blush, as mostly seems to be the case with Istvan's flower. Otherwise, probably, the correct designation might be 'alboflavescens' - or maybe 'flavoalbescens' would be even more appropriate as the yellow colour is certainly and fully present, while the slightly pinkish hue seems to affect only the white segments of David's flower (albecens means whittish/close to be(coming) white)!