[css-inline] result of initial-letter when sink substantially exceeds size

AFAICS, the current spec does not explicitly address the situation where 
the 'sink' value of an initial letter is much greater than its 'size':

   p::first-letter { initial-letter: 1.8 4; }

Is the following text of the paragraph expected to run _above_ the 
initial letter, or should the initial letter's exclusion area be assumed 
to extend upwards to the start of the paragraph?

JK