1. A compositions comprising:(A) at least one organopolysiloxane comprising at least 3 units of the formula

R1aR2bR3cHd(RO)eSiO(4-a-b-c-d-e)/2 (I),whereR1 each independently are monovalent, SiC-bonded, optionally halogen- or cyano-substituted hydrocarbyl moieties with aliphatic carbon-carbon multiple bonding,

R2 each independently are monovalent, SiC-bonded, optionally halogen- or cyano-substituted, saturated hydrocarbyl moieties,

R3 each independently are monovalent SiC-bonded aromatic moieties,

R each independently are hydrogen or monovalent, optionally substituted hydrocarbyl moieties which are optionally interrupted by heteroatoms,

a is 0, 1, 2 or 3,

b is 0, 1, 2 or 3,

c is 0, 1, 2 or 3,

d is 0, 1 or 2, and

e is 0, 1 or 2,with the proviso that the a+b+c+d+e sum is not more than 3, the sum total of Si-bonded hydrogen atoms and R1 moieties per molecule is at least 3, the a+b+c+d sum is equal to 0 or 1 in at least 10 mol % of the units of formula (I), c is other than 0 in at least one unit, and the ratio of Si-bonded hydrogen atoms to Si-bonded R1 moieties in the siloxane (A) is from 0.1 to 9,optionally (B) organopolysiloxanes comprising units of the formulaR4fR5gR6h(R7O)tSiO(4-f-g-h-i)/2 (VI),whereR4 each independently are monovalent, SiC-bonded, optionally halogen- or cyano-substituted, hydrocarbyl moieties with aliphatic carbon-carbon multiple bonding,

R5 each independently are monovalent, SiC-bonded, optionally halogen- or cyano-substituted, saturated hydrocarbyl moieties,

R6 each independently are monovalent SiC-bonded aromatic moieties,

R7 each independently are hydrogen or monovalent, optionally substituted hydrocarbyl moieties, which are optionally interrupted by heteroatoms,

f is 0, 1, 2 or 3,

g is 0, 1, 2 or 3,

h is 0, 1 or 2,

i is 0 or 1,with the proviso that the f+g+h+i sum is not more than 3, siloxanes (B) have at least two R4 moieties per molecule, the f+g+h+i sum is equal to 0 or 1 in not more than 20 mol % of the units of formula (VI) and h is other than 0 in at least one unit of formula (VI),(C) at least one organopolysiloxane comprising units of the formula

R8kR9lR10m(R11O)nSiO(4-k-l-m-n)/2 (X),whereR8 each independently are monovalent, SiC-bonded, optionally halogen- or cyano-substituted, hydrocarbyl moieties with aliphatic carbon-carbon multiple bonding,

R9 each independently are monovalent, SiC-bonded, optionally halogen- or cyano-substituted, saturated hydrocarbyl moieties,

R10 each independently are monovalent SiC-bonded aromatic moieties,

R11 each independently are hydrogen or monovalent, optionally substituted hydrocarbyl moieties, which are optionally interrupted by heteroatoms,

k is 0, 1, 2 or 3,

l is 0, 1, 2 or 3,

m is 0, 1 or 2, and

n is 0 or 1,with the proviso that the k+l+m+n sum is not more than 3, siloxanes (C) have at least two R8 moieties per molecule, the k+l+m+n sum is equal to 0 or 1 in at least 10 mol % of the units of formula (X) and m is other than 0 in at least one unit of formula (X),and

optionally, (D) a catalyst which promotes the addition of Si-bonded hydrogen onto aliphatic carbon-carbon multiple bonds.