David E. Hoffmann, writing in The Oligarchs: Wealth And Power In The New Russia:
The Soviet system also had another kind of funds, known as non-cash, or ‘beznalichnye’. This was not banknotes or coins, but a kind of virtual money that was widely distributed as government subsidies to factories. The ‘beznalichnye’, or ‘noncash’, existed only as an accounting unit. A factory would be transferred subsidies in beznalichnye, which it would record on its books and might use to pay another enterprise—but it was not something you could put in your wallet.
The key dilemma for a factory manager was that the system was rigid: mixing the two kinds of money was prohibited. The factory manager was not allowed to take the beznalichnye and turn it into real cash. Both kinds of money were controlled by Gosbank, the official state bank, and by the central planners.
However, factory managers almost always needed more cash than they could get out of the system. The supply of cash was tight, but the supply of beznalichnye was very plentiful — maybe because there was not much use for it. The result was an imbalance in the value of the two kinds of money. Cash was much more valuable and sought after. By some estimates, a cash ruble was worth ten times a noncash ruble.
This imbalance was an invitation to huge profits. Someone who figured out how to turn the beznalichnye into cash would make a fortune. The planners’ greatest nightmare was that someone would do this and pump the relatively worthless state subsidies into real cash rubles.
Guess who figured it out.