# Re: [NTG-context] reusing figures ok - problem with hiding blocks in MKIV

```On 15-1-2010 16:26, Matthias Weber wrote:
```
`Dear all,`
```
after (finally) installing the minimals,
the zip with the figures TeXs as expected with MKII and MKIV.

Now, in MKIV I notice another issue. I use the \hideblocks mechanism to
hide and reuse answers and get an error message (Undefined control
sequence) in MKIV while everything is fine
in MKII. I am attaching a sample file.
```
```

there are two issues:

\defineblock[exercise,solution]

```
i want to get away from the multiple definitions (for the moment i enabled it again in the upcoming beta) but the following should work in your case
```
\defineblock[solution]
\defineblock[exercise]

next, delete the tuc file and use the start/stop commands

\beginsolution
\startsolution
Solution one.
\stopsolution
\endsolution

```
\solution is ok but looks for a \par as delimiter so using the \start... \stop... variant is better
```
Hans

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