diff --git a/etc/options b/etc/options
--- a/etc/options
+++ b/etc/options
@@ -1,375 +1,375 @@
 (* :mode=isabelle-options: *)
 
 section "Document Preparation"
 
 option browser_info : bool = false
   -- "generate theory browser information"
 
 option document : string = ""
-  -- "build document in given format: pdf, dvi, false"
+  -- "build PDF document (enabled for \"pdf\" or \"true\", disabled for \"\" or \"false\")"
 option document_output : string = ""
   -- "document output directory"
 option document_variants : string = "document"
   -- "alternative document variants (separated by colons)"
 option document_tags : string = ""
   -- "default command tags (separated by commas)"
 option document_bibliography : bool = false
   -- "explicitly enable use of bibtex (default: according to presence of root.bib)"
 option document_preprocessor : string = ""
   -- "document preprocessor: executable relative to document output directory"
 option document_build : string = "lualatex"
   -- "document build engine (e.g. lualatex, pdflatex, build)"
 option document_logo : string = ""
   -- "generate named instance of Isabelle logo (underscore means unnamed variant)"
 
 option thy_output_display : bool = false
   -- "indicate output as multi-line display-style material"
 option thy_output_break : bool = false
   -- "control line breaks in non-display material"
 option thy_output_cartouche : bool = false
   -- "indicate if the output should be delimited as cartouche"
 option thy_output_quotes : bool = false
   -- "indicate if the output should be delimited via double quotes"
 option thy_output_margin : int = 76
   -- "right margin / page width for printing of display material"
 option thy_output_indent : int = 0
   -- "indentation for pretty printing of display material"
 option thy_output_source : bool = false
   -- "print original source text rather than internal representation"
 option thy_output_source_cartouche : bool = false
   -- "print original source text rather than internal representation, preserve cartouches"
 option thy_output_modes : string = ""
   -- "additional print modes for document output (separated by commas)"
 
 
 section "Prover Output"
 
 option show_types : bool = false
   -- "show type constraints when printing terms"
 option show_sorts : bool = false
   -- "show sort constraints when printing types"
 option show_brackets : bool = false
   -- "show extra brackets when printing terms/types"
 option show_question_marks : bool = true
   -- "show leading question mark of schematic variables"
 
 option show_consts : bool = false
   -- "show constants with types when printing proof state"
 option show_main_goal : bool = false
   -- "show main goal when printing proof state"
 option goals_limit : int = 10
   -- "maximum number of subgoals to be printed"
 
 option names_long : bool = false
   -- "show fully qualified names"
 option names_short : bool = false
   -- "show base names only"
 option names_unique : bool = true
   -- "show partially qualified names, as required for unique name resolution"
 
 option eta_contract : bool = true
   -- "print terms in eta-contracted form"
 
 option print_mode : string = ""
   -- "additional print modes for prover output (separated by commas)"
 
 
 section "Parallel Processing and Timing"
 
 public option threads : int = 0
   -- "maximum number of worker threads for prover process (0 = hardware max.)"
 option threads_trace : int = 0
   -- "level of tracing information for multithreading"
 option threads_stack_limit : real = 0.25
   -- "maximum stack size for worker threads (in giga words, 0 = unlimited)"
 
 public option parallel_limit : int = 0
   -- "approximative limit for parallel tasks (0 = unlimited)"
 public option parallel_print : bool = true
   -- "parallel and asynchronous printing of results"
 public option parallel_proofs : int = 1
   -- "level of parallel proof checking: 0, 1, 2"
 option parallel_subproofs_threshold : real = 0.01
   -- "lower bound of timing estimate for forked nested proofs (seconds)"
 
 option command_timing_threshold : real = 0.1
   -- "default threshold for persistent command timing (seconds)"
 
 public option timeout_scale : real = 1.0
   -- "scale factor for timeout in Isabelle/ML and session build"
 
 
 section "Detail of Proof Checking"
 
 option record_proofs : int = -1
   -- "set level of proofterm recording: 0, 1, 2, negative means unchanged"
 option quick_and_dirty : bool = false
   -- "if true then some tools will OMIT some proofs"
 option skip_proofs : bool = false
   -- "skip over proofs (implicit 'sorry')"
 option strict_facts : bool = false
   -- "force lazy facts when defined in context"
 
 
 section "Global Session Parameters"
 
 option condition : string = ""
   -- "required environment variables for subsequent theories (separated by commas)"
 
 option timeout : real = 0
   -- "timeout for session build job (seconds > 0)"
 
 option timeout_build : bool = true
   -- "observe timeout for session build"
 
 option process_output_limit : int = 100
   -- "build process output limit (in million characters, 0 = unlimited)"
 
 option process_output_tail : int = 40
   -- "build process output tail shown to user (in lines, 0 = unlimited)"
 
 option profiling : string = ""
   -- "ML profiling (possible values: time, allocations)"
 
 option system_log : string = ""
-  -- "output for system messages (log file or \"-\" for console progress)"
+  -- "output for system messages (log file or \"true\" for console progress)"
 
 option system_heaps : bool = false
   -- "store session heaps in $ISABELLE_HEAPS_SYSTEM, not $ISABELLE_HEAPS"
 
 
 section "ML System"
 
 option ML_print_depth : int = 20
   -- "ML print depth for toplevel pretty-printing"
 
 public option ML_exception_trace : bool = false
   -- "ML exception trace for toplevel command execution"
 
 public option ML_exception_debugger : bool = false
   -- "ML debugger exception trace for toplevel command execution"
 
 public option ML_debugger : bool = false
   -- "ML debugger instrumentation for newly compiled code"
 
 public option ML_system_64 : bool = false
   -- "ML system for 64bit platform is used if possible (change requires restart)"
 
 public option ML_process_policy : string = ""
   -- "ML process command prefix (process policy)"
 
 
 section "PIDE Build"
 
 option pide_reports : bool = true
   -- "report PIDE markup"
 
 option build_pide_reports : bool = true
   -- "report PIDE markup in batch build"
 
 
 section "Editor Session"
 
 public option editor_load_delay : real = 0.5
   -- "delay for file load operations (new buffers etc.)"
 
 public option editor_input_delay : real = 0.2
   -- "delay for user input (text edits, cursor movement etc.)"
 
 public option editor_generated_input_delay : real = 1.0
   -- "delay for machine-generated input that may outperform user edits"
 
 public option editor_output_delay : real = 0.1
   -- "delay for prover output (markup, common messages etc.)"
 
 public option editor_consolidate_delay : real = 2.0
   -- "delay to consolidate status of command evaluation (execution forks)"
 
 public option editor_prune_delay : real = 15
   -- "delay to prune history (delete old versions)"
 
 option editor_prune_size : int = 0
   -- "retained size of pruned history (delete old versions)"
 
 public option editor_update_delay : real = 0.5
   -- "delay for physical GUI updates"
 
 public option editor_reparse_limit : int = 10000
   -- "maximum amount of reparsed text outside perspective"
 
 public option editor_tracing_messages : int = 1000
   -- "initial number of tracing messages for each command transaction (0: unbounded)"
 
 public option editor_chart_delay : real = 3.0
   -- "delay for chart repainting"
 
 public option editor_continuous_checking : bool = true
   -- "continuous checking of proof document (visible and required parts)"
 
 public option editor_output_state : bool = false
   -- "implicit output of proof state"
 
 option editor_execution_delay : real = 0.02
   -- "delay for start of execution process after document update (seconds)"
 
 option editor_syslog_limit : int = 100
   -- "maximum amount of buffered syslog messages"
 
 public option editor_presentation : bool = false
   -- "dynamic presentation while editing"
 
 
 section "Headless Session"
 
 option headless_consolidate_delay : real = 15
   -- "delay to consolidate status of command evaluation (execution forks)"
 
 option headless_prune_delay : real = 60
   -- "delay to prune history (delete old versions)"
 
 option headless_check_delay : real = 0.5
   -- "delay for theory status check during PIDE processing (seconds)"
 
 option headless_check_limit : int = 0
   -- "maximum number of theory status checks (0 = unlimited)"
 
 option headless_nodes_status_delay : real = -1
   -- "delay for overall nodes status check during PIDE processing (seconds, disabled for < 0)"
 
 option headless_watchdog_timeout : real = 600
   -- "watchdog timeout for PIDE processing of broken theories (seconds, 0 = disabled)"
 
 option headless_commit_cleanup_delay : real = 60
   -- "delay for cleanup of already imported theories (seconds, 0 = disabled)"
 
 option headless_load_limit : real = 5.0
   -- "limit in MB for loaded theory files (0 = unlimited)"
 
 
 section "Miscellaneous Tools"
 
 public option find_theorems_limit : int = 40
   -- "limit of displayed results"
 
 public option find_theorems_tactic_limit : int = 5
   -- "limit of tactic search for 'solves' criterion"
 
 
 section "Completion"
 
 public option completion_limit : int = 40
   -- "limit for completion within the formal context"
 
 public option completion_path_ignore : string = "*~:*.marks:*.orig:*.rej:.DS_Store"
   -- "glob patterns to ignore in file-system path completion (separated by colons)"
 
 
 section "Spell Checker"
 
 public option spell_checker : bool = true
   -- "enable spell-checker for prose words within document text, comments etc."
 
 public option spell_checker_dictionary : string = "en"
   -- "spell-checker dictionary name"
 
 public option spell_checker_include : string = "words,comment,comment1,comment2,comment3,ML_comment,SML_comment"
   -- "included markup elements for spell-checker (separated by commas)"
 
 public option spell_checker_exclude : string = "document_marker,antiquoted,raw_text"
   -- "excluded markup elements for spell-checker (separated by commas)"
 
 
 section "Secure Shell"
 
 option ssh_config_dir : string = "$HOME/.ssh"
   -- "SSH configuration directory"
 
 option ssh_config_file : string = "$HOME/.ssh/config"
   -- "main SSH configuration file"
 
 option ssh_identity_files : string = "$HOME/.ssh/id_dsa:$HOME/.ssh/id_ecdsa:$HOME/.ssh/id_rsa"
   -- "possible SSH identity files (separated by colons)"
 
 option ssh_compression : bool = true
   -- "enable SSH compression"
 
 option ssh_connect_timeout : real = 60
   -- "SSH connection timeout (seconds)"
 
 option ssh_alive_interval : real = 30
   -- "time interval to keep SSH server connection alive (seconds)"
 
 option ssh_alive_count_max : int = 3
   -- "maximum number of messages to keep SSH server connection alive"
 
 
 section "Phabricator"
 
 option phabricator_version_arcanist : string = "7af9846f994a8d0a1fc89af996e3ddd81f01765e"
   -- "repository version for arcanist"
 
 option phabricator_version_phabricator : string = "2afedad61c5181bb4f832cea27b9b59df19f3fd5"
   -- "repository version for phabricator"
 
 
 section "Theory Export"
 
 option export_theory : bool = false
   -- "export theory content to Isabelle/Scala"
 
 option export_standard_proofs : bool = false
   -- "export standardized proof terms to Isabelle/Scala (not scalable)"
 
 option export_proofs : bool = false
   -- "export proof terms to Isabelle/Scala"
 
 option prune_proofs : bool = false
   -- "prune proof terms after export (do not store in Isabelle/ML)"
 
 
 section "Theory update"
 
 option update_inner_syntax_cartouches : bool = false
   -- "update inner syntax (types, terms, etc.) to use cartouches"
 
 option update_mixfix_cartouches : bool = false
   -- "update mixfix templates to use cartouches instead of double quotes"
 
 option update_control_cartouches : bool = false
   -- "update antiquotations to use control symbol with cartouche argument"
 
 option update_path_cartouches : bool = false
   -- "update file-system paths to use cartouches"
 
 
 section "Build Database"
 
 option build_database_server : bool = false
 option build_database_user : string = ""
 option build_database_password : string = ""
 option build_database_name : string = ""
 option build_database_host : string = ""
 option build_database_port : int = 0
 option build_database_ssh_host : string = ""
 option build_database_ssh_user : string = ""
 option build_database_ssh_port : int = 0
 
 
 section "Build Log Database"
 
 option build_log_database_user : string = ""
 option build_log_database_password : string = ""
 option build_log_database_name : string = ""
 option build_log_database_host : string = ""
 option build_log_database_port : int = 0
 option build_log_ssh_host : string = ""
 option build_log_ssh_user : string = ""
 option build_log_ssh_port : int = 0
 option build_log_history : int = 30  -- "length of relevant history (in days)"
 option build_log_transaction_size : int = 1  -- "number of log files for each db update"
 
 
 section "Isabelle/Scala/ML system channel"
 
 option system_channel_address : string = ""
 option system_channel_password : string = ""