[metapost] strings with > 4000 characters

[Mojca Miklavec]

Dear list,

I would like to ask if there is any trick that enables splitting
strings with > 4000 characters.

I would like to use
    substring (10000,10006) of some string

When drawing functions, one can scale down calculations towards lower
numbers and with some special care, one can still make it work. Is
there any similar trick (excluding metapost 2) for strings?

Thank you,
   Mojca