When a filled run is proven to be a particular clue block and already has exactly that clue's length, the block is completed. Any in-line cell immediately beside that block that could otherwise extend it must be empty, creating a separator.
Marking those separators immediately prevents illegal growth and often creates the next deduction.
Why a completed block must stop
Suppose a clue block has length 3 and you have identified three consecutive filled cells as that block.
If the next cell were also filled, the run would have length 4. That would violate the clue.
Therefore, unless the block touches the grid edge, the adjacent cell must be empty.
With standard monochrome clues, that empty cell also maintains the required separation from the next clue block.
Example with multiple clues
Consider a 12-cell line with clues 2 3. Cells 8–10 are confirmed filled in a way that identifies them as the final 3 block.
The cell immediately before it, cell 7, must be empty so the earlier 2 block cannot merge into the completed 3.
Because 3 is also the last clue and cells 8–10 already satisfy it, cells after the block cannot contain another filled run either.
The key deduction starts with block identity plus exact clue length.
Do not declare a block completed too early
A visible run of filled cells is not automatically a completed block just because its current length matches one of the clue numbers.
Suppose a line has clues 2 5 and you see two adjacent filled cells. Those cells might be:
- the complete
2block; or - only part of the unresolved
5block.
Until clue order, surrounding X marks, reach, or other constraints prove which block they belong to, placing separators could be wrong.
Separators are semantic empty cells
The X mark is only a visual representation. The logical fact is that the cell is confirmed empty.
That matters because the empty cell does more than “close” the block. It also:
- breaks the line into separate regions;
- restricts where other blocks can fit;
- may make a nearby gap too small;
- can create an exact fit in the remaining segment;
- gives the crossing line a new empty constraint.
Completed blocks at the edge
If a completed block touches the first or last cell of the line, there is no cell outside the grid to mark.
Only the in-grid side needs a separator when another filled cell there would illegally extend or merge the block.
The grid border itself is enough to stop the outer side.
When all clue blocks are completed
Once every clue block in a line is identified and complete, no additional filled cells are allowed anywhere else in that line.
All remaining unknown cells are therefore empty.
This is a powerful finishing step. A row that appears only partly marked may become completely solved as soon as its full clue sequence is accounted for.
Historical “Punctuating” terminology
Older technique lists sometimes call the habit of surrounding completed blocks with spaces Punctuating.
The name is memorable, but VeyraPlay uses completed blocks and separators because it says directly what is known and why the X marks are valid.
The underlying rule is the same: a completed block cannot be allowed to grow or merge with its neighbor.
Step-by-step process
When you think a block is complete:
- identify which clue number the filled run represents;
- count its filled cells;
- confirm that its length exactly matches that clue;
- confirm that extending the run would violate the clue assignment;
- mark the adjacent in-grid boundary cells empty where required;
- if all clues are now accounted for, mark every remaining cell empty;
- re-scan the crossing lines affected by those X marks.
Common mistakes
Matching by length alone
A run of two filled cells on a 2 5 line is not necessarily the 2 block. It could still grow into the 5.
Forgetting the separator between monochrome blocks
Two consecutive clue blocks cannot touch. A separator is part of the clue structure, not optional notation.
Adding an X outside the grid conceptually
No extra space is required beyond the line boundary.
Leaving known empty cells unmarked
Once a separator is proven, record it. Delaying X marks hides useful information from crossing lines.
What to learn next
Completed-block separators often divide a line into useful segments. From there, gap elimination and line segmentation determine what the remaining clues can still occupy.
FAQ
Should I always put an X beside a completed block?
If an in-grid adjacent cell being filled would extend or merge the identified completed block illegally, that cell is empty and should be marked. Edge cases depend on the block's position and clue assignment.
What if the filled run has the right length but I am not sure which clue it is?
Do not close it as a completed block yet. First prove its clue identity.
What happens when every clue in the line is complete?
Every remaining unknown cell is empty because no additional filled block is allowed by the clue sequence.