additionally receive the witness discount, making inscription content storage
relatively economical.

Since taproot script spends can only be made from existing taproot outputs,
inscriptions are made using a two-phase commit/reveal procedure. First, in the
commit transaction, a taproot output committing to a script containing the
inscription content is created. Second, in the reveal transaction, the output
created by the commit transaction is spent, revealing the inscription content
on-chain.

Inscription content is serialized using data pushes within unexecuted
conditionals, called "envelopes". Envelopes consist of an `OP_FALSE OP_IF …
OP_ENDIF` wrapping any number of data pushes. Because envelopes are effectively
no-ops, they do not change the semantics of the script in which they are
included, and can be combined with any other locking script.

A text inscription containing the string "Hello, world!" is serialized as
follows:

```
OP_FALSE
OP_IF
  OP_PUSH "ord"
  OP_PUSH 1
  OP_PUSH "text/plain;charset=utf-8"