The holdlock, noholdlock, and shared options can be specified for each table in a select statement, with the at isolation clause applied to the entire query.
select select_list from table_name [holdlock | noholdlock] [shared] [, table_name [[holdlock | noholdlock] [shared] {where/group by/order by/compute clauses} [at isolation { [read uncommitted | 0] | [read committed | 1] | [repeatable read | 2]| [serializable | 3]]
Here is the syntax for the readtext command:
readtext [[database.]owner.]table_name.column_name text_pointer offset size [holdlock | noholdlock] [readpast] [using {bytes | chars | characters}] [at isolation { [read uncommitted | 0] | [read committed | 1] | [repeatable read | 2]| [serializable | 3]}]