Element Selection

A place denotes a single element, or the position following that element. It can be specified by one of the choices

object-name[index]

The name verb'object-name' is the name of an element, line or sequence, and the integer index is its occurrence count in the beam line. If the element is unique, [index] can be omitted.

#S

denotes the position before the first physical element in the full beam line. This position can also be written #0.

#E

denotes the position after the last physical element in the full beam line.

Either form may be qualified by one or more beam line names, as described by the formal syntax:

place ::= element-name |
          element-name "[" integer "]" |
          "#S" |
          "#E" |
          line-name "::" place

An omitted index defaults to one. Examples: assume the following definitions:

M: MARKER;
S: LINE=(C,M,D);
L: LINE=(A,M,B,2*S,A,M,B);
   SURVEY,LINE=L

The line L is equivalent to the sequence of elements

A,M,B,C,M,D,C,M,D,A,M,B

Some possible place definitions are:

C[1]

The first occurrence of element C.

#S

The beginning of the line L.

M[2]

The second marker M at top level of line L, i. e. the marker between second A and the second B.

#E

The end of line L

S[1]::M[1]

The marker M nested in the first occurrence of S.