[metapost] Metapost doesn't like `z01' for point names

[Hartmut Henkel]

On Sun, 17 Jun 2007, Rodolfo Medina wrote:

> Please excuse the basic question.
> If I name a point `z01' Metapost complains:
>
> %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
> %file test.mp
> beginfig(1);
>
> z0 = (0,0);
> z1 = (1,1);
>
> z01 = 0.5[z0,z1];
>
> endfig;
>
> end
> %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
>
> $ mpost test
> This is MetaPost, Version 0.641 (Web2C 7.4.5)
> (test.mp
> ! Inconsistent equation (off by -0.5).
> <to be read again>
>                    ;
> l.8 z01 = 0.5[z0,z1];
>
> ?
>
>
> Instead, if I name it `z11' it's okay.  Why?  I really would like to name it
> `z01': is it definitely impossible?

z01 == z1 == z[1] == e. g. z0001.0 due to MetaPost's token rules, see e.
g. MFBook p. 50. And z1 was defined already. Numeric suffixes even
include the decimal point, another example: z.0100 == z.01 == z[0.01].

Regards, Hartmut