Liblouis User's and Programmer's Manual

2.5 Opcodes for Standing Alone Sequences ¶

The term “standing alone” comes from the specification of Unified English Braille (UEB). In Liblouis, a letter or letters-sequence is considered to be standing alone if it is preceded and followed by a space, and/or other characters that you choose as delimiters, e.g. ‘-’. A standing alone sequence can be thought of as a word in a very broad sense. With the opcodes described in this section, you can decide what characters constitute a delimiter, and what characters can attach to the beginning or end of a word or standing alone sequence.

Note: The opcodes in this section were implemented in Liblouis specifically in order to support Unified English Braille (UEB). They may be used in any table, but may have unpredicted side-effects if used outside the intended context. Use with great care, and test thoroughly.

seqdelimiter <characters>

All the characters listed with this opcode designate a valid beginning and ending to a letter sequence used to determine when a letter sequence is standing alone. This again determines whether word contractions (see word) or nocontractsign (see nocontractsign) should be applied.

Spaces do not need to be listed as they are automatically delimiters.

For example, in UEB (section 2.6.1 page 15), any hyphen or dash count as delimiters.

This opcode can be used several times, but the characters must have already been defined.

Example:

seqdelimiter -—

seqbeforechars <characters>

Characters specified with this opcode may appear between a beginning sequence delimiter and the letter sequence itself.

For example, in UEB (2.6.2, page 15), opening parenthesis and opening quotations and such are allowed.

This opcode can be used several times, but the characters must have already been defined.

Example:

seqbeforechars ([{"“'‘

seqafterchars <chars>

Characters specified with this opcode may appear between a letter sequence itself and an end sequence delimiter.

For example, in UEB (2.6.3, page 16), closing parenthesis and closing quotations and such are allowed.

This opcode can be used several times, but the characters must have already been defined.

Example:

seqafterchars  )]}"”'’.,;:.!?…

seqafterpattern <string>

Specifies that a specific string of characters can be between the letter sequence itself and an ending sequence delimiter.

For example, in UEB (section 2.6.4, page 18), the ‘'d’, ‘'s’, ‘'ll’, ‘'ve’, etc. can be after a letter sequence provided the overall sequence is standing alone.

This opcode may be used multiple times, once per pattern.

Example:

seqafterpattern 'd