In "Lecture Notes on Cryptography" what does "PTM" mean? I came across a handbook named "Lecture Notes on Cryptography" from Shafi Goldwasser and Mihir Bellare and I read their definition 3.1 about poly-time indistinguishability:


  Let $X_n,Y_n$ be probability distributions on $\{0,1\}^n$ (That is, by $t\in X_n$ we mean that $t\in\{0,1\}^n$
  and it is selected according to the distribution $X_n$).
  
  We say that $\{X_n\}$ is poly-time indistinguishable from
  $\{Y_n\}$ if $\forall \text{PTM } A, \forall \text{polynomial } Q, \exists n_0, \text{s.t. } \forall n&gt;n_0$,
  
  $$\left|\Pr_{t\in X_n}(A(t)=1)-\Pr_{t\in Y_n}(A(t)=1)\right|&lt;\frac1{Q(n)}$$


What I don't understand is what "PTM" means, can you please explain it to me?
As pointed out by hakoja in the comments:


  It means Probabilistic Turing Machine, see Section B.2.1.


where the following is written (emphasis mine, this is the full section B.2.1):


  Let $M$ denote a probabilistic Turing machine (PTM). $M(x)$ will denote a
  probability space of the outcome of $M$ during its run on $x$. The
  statement $z\in M(x)$ indicates that $z$ was output by $M$ when running on
  input $x$. $\Pr[M(x) = z]$ is the probability of $z$ being the output of $M$ on
  input $x$ (where the probability is taken over the possible internal
  coin tosses made by $M$ during its execution). $M(x; y)$ will denote the
  outcome of $M$ on input $x$ when internal coin tosses are $y$.