Ribonucleic acid (RNA) deserves not only a dedicated field of biological research -- a discipline or branch of knowledge -- but also explicit definitions of its roles in cellular processes and molecular mechanisms. Ribogenomics is to study the biology of cellular RNAs, including their origin, biogenesis, structure and function. On the informational track, messenger RNAs (mRNAs) are the major component of ribogenomes, which encode proteins and serve as one of the four major components of the translation machinery and whose expression is regulated at multiple levels by other operational RNAs. On the operational track, there are several diverse types of RNAs--their length distribution is perhaps the most simplistic stratification--involving in major cellular activ-ities, such as chromosomal structure and organization, DNA replication and repair, transcriptional/post-transcriptional regulation, RNA processing and routing, translation and cellular energy/metabolism regulation. An all-out effort exceeding the magnitude of the Human Genome Project is of essence to construct just mammalian transcriptomes in multiple contexts including embryonic development, circadian and seasonal rhythms, defined life-span stages, pathological conditions and anatomy-driven tissue/organ/cell types.