considered to have an implicit input equal in size to the subsidy, followed by
an input for every fee-paying transaction in the block, in the order that those
transactions appear in the block. The implicit subsidy input carries the
block's newly created sats. The implicit fee inputs carry the sats that were
paid as fees in the block's transactions.

Underpaying the subsidy does not change the ordinal numbers of sats mined
in subsequent blocks. Ordinals depend only on how many sats could have been
mined, not how many actually were.

=== Specification ===

Sats are numbered and transferred with the following algorithm:

<pre>
# subsidy of block at given height
def subsidy(height):
  return 50 * 100_000_000 >> height // 210_000

# first ordinal of subsidy of block at given height
def first_ordinal(height):
  start = 0
  for height in range(height):
    start += subsidy(height)
  return start

# assign ordinals in given block
def assign_ordinals(block):
  first = first_ordinal(block.height)
  last = first + subsidy(block.height)