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The interpretations of the various strings from  , the set of strings over  , along with the conventions for resolving conflicts, follow. |
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Let I be an arbitrary string from . In I a symbol is said to be quoted if the symbol ' occurs at its immediate left. I is parsed into broadcast units as follows: The first broadcast unit is designated by the segment from the leftmost unquoted * to (but not including) the next unquoted * on the right (if any). (Any prefix to the left of the leftmost unquoted * is ignored.) The second, third, etc., broadcast units are obtained by repeating this procedure for each successive unquoted * from the left. If I contains no unquoted * s it designates the null unit, i.e., it does not broadcast a signal under any condition. Thus |
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designates two broadcast units, namely |
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There are four types of broadcast unit (other than the null unit). To determine the type of a broadcast unit from its designation, first determine if there are three or more (unquoted) : to the right of the *. If so ignore the third : and everything to the right of it. The remaining substring, which has a * at the initial positions and at most two : s elsewhere, designates one of the four types if it has one of the following four organizations. |
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1. *I1 :I2 |
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2. *: I1: I2 |
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3. *I1: :I2 |
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4. *I1 :I2 :I3 |
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where I1, I2, and I3 are arbitrary non-null strings from except that they contain neither unquoted * s nor unquoted : s. If the substring does not have one of these organizations it designates the null unit. The four basic types have the following functions (subject to the conventions for eliminating ambiguities, which follow). |
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1. *I1 :I2If a signal of type I1 is present at time t, then the signal I2 isbroadcast at time t + 1. |
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2. *: I1:I2If there is no signal of type I1 present at time t, then the signal I2 is broadcast at time t + 1. |
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3. *I1: :I2If a signal of type I1 is present at time t, then a persistent string of type I2 (if any exists) is deleted at the end of time t. |
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