Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Block Shelves for Visual Programming Languages   The blocks editor, such as the editor in Scratch, is widely applied for
visual programming languages (VPL) nowadays. Despite it's friendly for
non-programmers, it exists three main limitations while displaying block codes:
(1) the readability, (2) the program structure, and (3) the re-use. To cope
with these issues, we introduce a novel formatting tool, block shelves, into
the editor for organizing blocks. A user could utilize shelves to constitute a
user-defined structure for the VPL projects. Based on the experiment results,
block shelves improves the block code navigating and searching significantly.
Besides, for achieving code re-use, users could use shelf export/import to
share/re-use their block codes between projects in the file format of
eXtensible Markup Language (xml.) All functions were demonstrated on MIT App
inventor 2, while all modifications were made in Google Blockly.

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The categories of this paper are: q-bio
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The categories of this paper are: nlin
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The categories of this paper are: ao-sci
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The categories of this paper are: alg-geom
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The categories of this paper are: math
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The categories of this paper are: hep-lat
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The categories of this paper are: math-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: acc-phys
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The categories of this paper are: q-alg
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The categories of this paper are: atom-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: econ
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The categories of this paper are: plasm-ph
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The categories of this paper are: adap-org
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The categories of this paper are: dg-ga