We define likelihood of parameters $\theta$ given observations $x$ (assuming $x$ is sampled according to density $f$) as:
$$\mathcal{L}(\theta | x)=f\_\theta(x).
$$
**Is it correct to speak about "[l]ikelihood of the data"** (The Elements of Statistical Learning before equation (2.35)), or should we only speak about the likelihood of parameters?

I also get such remark during oral presentation, but I'm still confused to know if this misnomer is accepted.

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In addition, the first equation comes from the English Wikipedia, but in the French ones it is written:
$$\mathcal{L}(x | \theta)=f(x;\theta).$$
I think this notation $\mathcal{L}(x | \theta)$ is incorrect, but is it accepted somehow? 
Are there some authoritative notation rules for likelihood, or each author picks as he wants?