Cash segmentation in corporate treasury

Please write a short article on cash segmentation in corporate treasury.
Cash segmentation means an organization can segment its liquidity portfolio into three categories, reflecting their different liquidity needs and risk profiles: Operating cash, Reserve cash and finally Strategic Cash.
Focus on the look on the techniques and processes – NOT the definition or general “blabla”.
Key questions should be:
To what extent is it generally useful/necessary to segment cash?
How far have goals changed under current economic circumstances?
How should treasurers be responding, in terms of segmentation, in light of this environment?
What techniques/models are being used to segment most effectively?
How many categories/levels of segmentation are most effective/ how often should segmentation review be undertaken?