Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Physics of ELFE   This paper presents an overview of the physics program of the 15-30~GeV
continuous beam electron facility proposed by the European community of nuclear
physicists to study the quark and gluon structure of hadrons. The goal of this
new facility is to explore the quark structure of matter by exclusive and
semi-inclusive electron scattering from nuclear targets.

25
The categories of this paper are: patt-sol
17
The categories of this paper are: q-fin
19
The categories of this paper are: eess
36
The categories of this paper are: cmp-lg
10
The categories of this paper are: q-bio
11
The categories of this paper are: hep-lat
14
The categories of this paper are: math-ph
30
The categories of this paper are: q-alg
29
The categories of this paper are: funct-an
28
The categories of this paper are: alg-geom
7
The categories of this paper are: hep-th
13
The categories of this paper are: quant-ph
34
The categories of this paper are: chem-ph
31
The categories of this paper are: ao-sci
26
The categories of this paper are: bayes-an
8
The categories of this paper are: hep-ex